# Will it work to place a canister just below the tank?



## cholile (Oct 28, 2007)

I hope to use a canister filter (maybe marineland C-360?) as a filter for two 33 gallon long (48" x 12" x 13") tanks that will be one on top of the other. The top tank is pre-drilled with a hole in the top right corner so I plan to have the water from the canister filter flow into the top tank and then drain from the top tank into the lower tank and then have the canister take the water from the bottom tank into the canister itself.

The first question is whether a canister filter that is, say, 17" tall, can be placed next to a tank that is 19" to 22" tall? In other words, if the canister filter is below the tank does it matter if it is literally just below the tank?

The second question is flow rate: 
a) How much flow can I have for the top tank (it will house demasoni and yellow labs) that will not be too much, but will be enough to ensure both tanks are well-filtered?
b) Which canisters can one adjust the flow-rate with?


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## Riceburner (Sep 3, 2008)

if the top tank is draining into the bottom tank...what keeps it from emptying? and what about a power outage?


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## trigger (Sep 6, 2002)

It's a tricky setup like this indeed. A canister filter needs to be under an tank, because it is designed to push water up. What needs to be is that the top of the filter canister is a given distance below the water surface. It does not litterlly be under the tank though, as long as you are well enough under the water level of the tank. Also the distance between the canister and the water level can not be more than a given distance. If that is too high, the pump just can not push the water far enough up to reach the tank. The minimum and maximum heights are descibed in the filter/pumps manual.


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## trigger (Sep 6, 2002)

Found the quick setup manual of the C360:
http://www.marineland.com/sites/Marinel ... esQSUG.pdf
It should be placed under the tank with the bottom of the canister between 32 and 60 inches from the water surface in the tank.


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## JALOOS (Sep 6, 2008)

trigger said:


> If that is too high, the pump just can not push the water far enough up to reach the tank.


With a closed loop system such as the canisters the water isn't being pumped from the canister to the top of the tank. The syphon pulls the water out of the tank through the canister and back up to the water level of the tank. The pump in the canister is there to overcome the last few inches from the water level over the lip of the tank and back into the tank. So in effect the pump is only actually pumping the water a few inches not all the way up from the canister.


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## RyanR (Apr 29, 2008)

The canister won't work like that, and it'd be cheaper to just run two HOB's.

-Ryan


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## Toby_H (Apr 15, 2005)

Jaloos' post is completely accurate and is an exceptionally important fact in regards to this set up...

The reason the canister is supposed to be at least x inxhes below the water surface is to allow the siphon to have a certain amount of momenteum... but it cannot be more than Y inches below the tank because then the weight of the water becomes too great.

Canister filters are not designed to deal with lifting water a number of feet, they are designed to deal with lifting water a number of inches... This is because they use magnetic driven pumps which use smaller magnets.

There are methods commonly used to 'break the siphon' which prevent wate from backflowing in the case of a power failure. This 'problem' must be overcome in every sump set up...

I suggest to either filter each tank seperately or use a water pump that is designed to lift water with appropriately designed plumbing...


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## cholile (Oct 28, 2007)

The top portion of the top tank is not too high off the ground. Definitely under 60 inches off the ground (where the bottom of the canister will be located).

The reason I want to use this route is so the two tanks are part of one system. It'll be easier to keep the water at a set temperature, I'll only need one heater and there are no HOB filters that will distract from viewing the tank. Each tank will just have one skinny hose (one has the inlet and the other the outlet).

Someone asked how the top tank can be prevented from draining in a power outage. I think actually this may be a problem with a canister filter. Only a small portion would drain so the fish would be fine, but I'd end up with maybe 2 to 4 gallons of water on the floor. Not pretty.

Ok, so what about a sump for the two tanks. Is it too small to use a bucket (maybe 8 gallons) as a sump? I would have the top tank drain into the bottom tank via the hole in the top right corner and the bottom tank, via the hole drilled in the top right corner of that tank, will drain into the sump bucket. Then, the pump at the bottom of the sump bucket will push the water back to the top tank.

Since I'd need about 4 gallons of room when the system would shut off the bucket would need to have no more than 4 gallons of water in it when the system was running.

I only have a space that is about 12" x 12" x 18" for the sump and with a round bucket I imagine I'd end up with about 8 or, at most, 10 gallons of space in the bucket.

Thoughts?


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## RyanR (Apr 29, 2008)

If the top tank is drilled, just put a submersible pump (capable of pumping several feet of head) in the lower tank, pumping into the upper tank, with the return going back into the bottom tank. That'll keep both tanks as the same system. Then put a canister on the top tank... or an HOB on both... or just the bottom tank.

-Ryan


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## Toby_H (Apr 15, 2005)

The above pic is of two 50 gal tanks (48" x 18" @ 13" tall) stacked above a standardd 75 gal tank... the two 50 gal tanks are drilled, the 75 is not... Water is pumped from the 75 gal up to the top 50 gal... falls through an overflow (drilled hole) and into the lower 50 gal... falls through an overflow (drilled hold) and back into the 75 gal on bottom...

This is the same concept you are suggesting although you wish to use an 8 gallon bucket for the bottom tank... and 33 gallon tanks for the top tanks...

So yes it is possible... it just needs to be designed right...

To prevent any kind of "siphoning" when the pumps are turned off, I split the return pipes allowing most of the water to flow through one side extending this pipe below the water's surface and left the other above the waters surface. This approach minimized the sound of splashing water yet immediately broke the potential siphon when the pump was turned off. Only the amount of water in the pipe fell into the bottom tank from this side...

As this set up relies on the force of gravity to push the water through the overflow (drilled holes) the water level will rise slightly above the bottom of the overflow hole. This means when the pump is turned off the water will continue to fall through the overflow until it reaches the bottom of the overflow's hole. Be sure to account for this water in your lower tank and sump...

In your situation I would look for a 12" x 12" @ 18 inch tall container to initially explore with... although I personally do not think this will be a big enough container in practical application. Also remember that per design the water level on the upper two tanks will be constant, meaning the evaporation from all three tanks will all come off the water level of the bottom tank. as your bottom tank will have 1/4 the surface space of each upper tank... this means evaporation will have a very compounded effect on the water level in your 12" x 12" sump... This sump will probably need to be topped off daily which means no falling asleep early, no forgetting, no going on vacation, etc, etc...

Having experience at the approach, I definitely like the idea of plumbing tanks together and value the benefits such a set up offers... but in all practicality I just donâ€™t think the set up you are describing is the best place to employ such an approach. If you could manage to put a third 33 gallon beneath your set up I would change my mind.

If you choose to take this approach, do be sure to use a water pump designed to lift water and not ask a canister to do a job it is not designed to do...


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## cholile (Oct 28, 2007)

I don't intend to use a canister anymore, but I'm not sure I understand the problem of the canister pushing the water back into the tank. The canister would have to push the water an even shorter distance in this setup than it would typically have to do if it were sitting in a 2.5' stand and pushing the water above that into a tank that is 24" to 30" tall.

In any event, I don't like the idea of a pump in the tank as it's not aesthetically appealing to me and I wouldn't be able to really hide it. I'd still need another filter anyway too.

So the question is whether I can do something like this: 




Only I would use a container that is only 12" x 12" x 18" (that's just over 11 gallons). When running it'd be filled with about 4 to 5 gallons of water as that would allow enough excess room for the sump to fill with water without overflowing the sump.


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## Toby_H (Apr 15, 2005)

cholile said:


> I don't intend to use a canister anymore, but I'm not sure I understand the problem of the canister pushing the water back into the tank. The canister would have to push the water an even shorter distance in this setup than it would typically have to do if it were sitting in a 2.5' stand and pushing the water above that into a tank that is 24" to 30" tall.


I understand you've decided not to use a canister, but just for information purposes...

When you have a canister set up in the conventional way... and you turn the motor off and wait for the water to find it's balance point, provided the canister's body does not have air in it... the water will fill the intake tube (even above the water surface of the tank) all the way to the canister's body, the canister's body will be filled with water, as will the return tube up to the aquarium's water surface... This is all achieved by gravity...

Therefore the pump only has to push the water up a couple of inches to make it over the lip of the tank...

If the intake were on a tank 24~36" lower than the top tank... and the canister's power was turned off the water would balance at the water's surface of the bottom aquarium... and when turned on would have to lift the water up 24~36" to go over the lip of the top aquarium... Canister filters are not designed to deal with this sort of lift...



cholile said:


> In any event, I don't like the idea of a pump in the tank as it's not aesthetically appealing to me and I wouldn't be able to really hide it. I'd still need another filter anyway too.


The pump does not need to be an internal pump... Many water pumps can be connected inline and therefore kept outside of the aquarium. But as you mentioned, you would most likely still want some form of additional filtration.

On the 3 aquarium tier I pictured above, the bottom tank (75 gal) has 2x AC 110s, there is a 700 gph pump used to push water from the bottom tank to the top tank and no other filtration is used. Biological needs are met as bacteria grows on all surfaces, not just in filter media. Mechanical filtration was not very strong but I kept them clean via weekly water changes. Chemical filtration was simply not necessary due to regular water changes.



cholile said:


> So the question is whether I can do something like this:
> 
> 
> 
> ...


Essentially, your question is "can I set up a typical sump"... and the simple answer is yes...

Setting up a sump for two tanks stacked one above the other is not much different at all from setting up a sump for a single tank. Simply repeat the exact same overflows on each tank allowing the top tank to flow into the bottom tank and the bottom tank to flow into the sump. One downside to this approach is waste from the top tank is pushed into the bottom tank making the bottom tank much more likely to appear dirty.

Theoretically there is no reason why you cannot use the 12" x 12" @ 18" container as a sump for your two 48" x 12" @ 13' 33 gal tanks... practically speaking the 12" x 12' @ 18" sump is not very large and will pose some restrictions reducing practicality. Using smaller plumbing will minimize the amount of water you have returning to the sump when the pump is turned off, but will also limit the size of the pump you are able to use.

The diameter of the hole drilled in your 33 gal aquariums and the actual flow rate of your pump will dictate how high above the bottom of the hole the water will build... If, for example, it builds 1" on your 48" x 12" tank... then when the pump is turned off and this drains into your 12" x 12" sump it will raise the level of the sump by 4". Multiply this by 2 as you have two aquariums that will be back draining into the sump. Add another inch or so for the water coming down the pipe from the return pump to the top tank... then another inch or two for water in the overflow pipes.

After reviewing the numbers above I do not think your system will function well if the water builds up more than 1" above the bottom of the overflow hole. So I think this system will only work with a small pump (low actual gph).

Also bare in mind what I mentioned earlier about evaporation and it's compounded effect of lowering the level of the sump.

In conclusion... yes it is theoretically possible to create the system you are suggesting... but in my experience with such systems no it is not practical to do so with such a small sump. In my experience when plumbing multiple tanks to a single sump, a larger sump than typical is needed and you are suggesting using a smaller sump than typical.


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## Toby_H (Apr 15, 2005)

Double Post  oops...


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## cholile (Oct 28, 2007)

Thanks toby! so helpful. I don't fully understand the canister filter comment, but maybe that's part of why I've never been interested in canister filters. If my tank is small and I can't use a sump I find the HOB cheaper, simpler, and plenty sufficient. If the tank is larger then I may as well use a sump.

As for the sump idea I did not think through just how much room I would need for the water flowing into the sump. I think the holes are 1" diameter.

Ok, so maybe I'm just trying to force what cannot be done, but what about the following:

the footprint of the sump will have to be 12" x 12" There's no getting around that given what I want to do. But suppose I found something like that which was very tall (e.g. maybe a tall and skinny garbage can). Then, I would put the pump at the bottom of the trash can and right next to it a bucket or plastic tower of drawers and drill a hole in the side of the trash can about 18" above the bottom of the trash can. Then the pipe draining from the lower tank would flow into the trash can at the 18" level. While running the water would be filled only about 10" or so, but when it shut off there would be room for the water to flow up well above the pipe draining into the trash can.

Does that make sense? Could that work?


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## frank1rizzo (Mar 14, 2005)

Toby_H said:


> Therefore the pump only has to push the water up a couple of inches to make it over the lip of the tank...


And it has to push the water through the filter media as well. The more media (the finer the media), more resistance is added, and the flow is restricted accordingly.

Just though I would add that point for completeness.


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## Toby_H (Apr 15, 2005)

cholile said:


> Thanks toby! so helpful. I don't fully understand the canister filter comment, but maybe that's part of why I've never been interested in canister filters. If my tank is small and I can't use a sump I find the HOB cheaper, simpler, and plenty sufficient. If the tank is larger then I may as well use a sump.


I'd be happy to try to answer any specific questions or reexplain any specific points that aren't clear... but I don't want to 'beat a dead horse'... I'm sure if we were in a room together with a tank and a canister you could understand it... text only explainations are always difficult...



cholile said:


> As for the sump idea I did not think through just how much room I would need for the water flowing into the sump. I think the holes are 1" diameter.


My 50 gal tanks (pictured above) as well as a few 30 gals I have are drilled with 1" holes. I was not able to find an actual bulkhead with a 1" diameter OD but found that 1/2" ID PVC fits in with just a little wiggle room. I was able to make sealed connections through my 1" holes with it. I used the PVC glue on the PVC to PVC connection as well as siliconed the PVC to the glass. At first I only truested this seal to go in my garage fishroom, but after having it out there for a year I trusted it enough to move tanks with this seal into my living room.



cholile said:


> Ok, so maybe I'm just trying to force what cannot be done,


I don't think your trying to force anything... just thinking/talking your way through an idea and not giving up until it makes sense why it won't work. So9unds like an intelligent guy in a learning process to me...



cholile said:


> but what about the following:
> 
> the footprint of the sump will have to be 12" x 12" There's no getting around that given what I want to do. But suppose I found something like that which was very tall (e.g. maybe a tall and skinny garbage can). Then, I would put the pump at the bottom of the trash can and right next to it a bucket or plastic tower of drawers and drill a hole in the side of the trash can about 18" above the bottom of the trash can. Then the pipe draining from the lower tank would flow into the trash can at the 18" level. While running the water would be filled only about 10" or so, but when it shut off there would be room for the water to flow up well above the pipe draining into the trash can.
> 
> Does that make sense? Could that work?


Give us a better description of the set up you are proposing... What you are proposing is possible... and the way to increase it's practicality is to reduce the size of the pump... but if you reduce the size of the pump too much it may simply prove too slow of a flow rate to make it worth the effort/investment.

How high off the ground is the bottom of your lower 33 gal tank? Do you have any space directly beneath it to work with?

Will the sump / garbage can / 12" x 12" @ 18" container sit next to the 33 gal aquariums that are stacked one above the other?

Give us a description of the stand the 33 gals will be on...

Am I correct that the approx 1" diameter holes are drilled near the top of the 33 gal tanks on the back wall (right hand side I believe you said)? Do you have bulkheads for the drilled holes?

If you could include a picture of the space the tanks will be stacked in that would help me/us get a visual and possibly think of additional approaches to consider.

One other idea I have that you or others may want to consider and share ideas with is using one sump for both tanks... but have a seperate pump for each tank. This would give you the freedom of using a larger pump for the higher tank and only limit the size of the pump on the lower tank. This would also remove the concern of pulling waste from the upper tank into the lower tank...

If you were to attempt the above idea would it be practical to use an HOB on the lower tank and not the upper? As I feel this set up could be designed quite practically using your garbage can sump idea...


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## cholile (Oct 28, 2007)

The tanks will be on your typical iron stand (presumably people usually use the top portion for a standard 55G tank).

So the bottom tank is almost exactly 7" off the ground. The tanks are either 12" or 13" tall (don't have it in front of me at the moment). The holes are indeed drilled near the top of the tank. At most an inch from the top of the glass, but I think closer to 1/2 or 3/4 an inch from the top. I do have the bulkheads for both, along with the piece (not sure the term) that prevents fish from entering the hole and perhaps also is designed to reduce flow/noise.

The idea is to have in the corner of the room these twin 33G on one wall and then the twin 15g tanks I have on another iron stand on the other wall in the corner. So the tanks would form a right angle.

I don't have a picture b/c it is not set up yet. But if you can visualize it, then when the tanks are pushed next to each other in the corner of the room you would be left with a square space between them in the corner. Of course my tanks are shorter and with iron stands so accessing that corner will not be too hard (as opposed to with tanks like that where it'd be nearly impossible).

If I can't use one sump and one pump for the whole system then it'll probably just be as easy to use HOB and heater for each tank. It's certainly not the end of the world if I do that, but having the tanks drilled means if I can create a sump system for both to get the benefits of a sump then I might as well go for it.

If I used a mag 7 then, because the sump will be right next to the tank it'd go, at most, 4 feet, so there would be roughly 450 GPH, which seems both enough for a 75 gallon system and hopefully not too overwhelming for the 33G (I might have to try a spray bar or something to disperse it a little. The top tank will be demasoni and yellow labs).

I think I answered all of your questions, but if you're anything like me then that may not be enough as seeing something visually really helps make sense of what's written.


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## Toby_H (Apr 15, 2005)

I do understand the idea of having two separate racks meeting at a 90* angle in the corner of a room... which does leave an unused square in the corner of the room where you wish to put the sump/container... That makes a lot of sense to utilize this space as such if at all possible/practical...

The first thing I would like to point out is that if you were to expand the sump to 16" x 16" (instead of 12" x 12")... by pulling the tanks 4" out from the wall or by allowing a few inches of the sump to show between the racks... At 12" depth you will almost double the volume of the sump...

12" x 12" @ 12" deep = 7.48 gal; 16" x 16" @ 12" deep = 13.30 gal... This has the potential of being a critical difference...

The 1" diameter holes drilled in the 33 gal tanks will most likely accommodate a 1/2" ID pipe/hose, possibly 3/4" (please check the ID of your bulkheads to confirm the diameter). a 1/2" ID is not very big and will not facilitate very much flow. So although the sump may be able to be managed, it may not give you the turnover rates you will want for mechanical filtration. Powerheads or strong cleaning regiments may be the best solutions for this.

Calculating the "turnover per hour" of this system will be a bit tricky. When calculating Bio Filtration, you will want to use the factor of the entire systems volume. Meaning if the entire system is 80 gallons and the actual flow rate of the pump is 400 gph, then for bio filtration you are turning the system over 5 times per hour (400/80)...

Calculating the "turnover per hour" for mechanical filtration you will want to consider each tank individually. Using the same pump flow rates as above, putting 400 gallons per hour into the top 33 gallon tank will cause the effective current in that 33 gal tank to be slightly over 12 times per hour (400/33). This same current will then be re-gathered (at the overflow between the first and second tank) and then redistributed in the lower 33 gallon tank.

To paint a clearer picture of this... consider a standard sump set up with a 400 gallon tank using a 40 gallon sump... if the pump involved had an actual flow rate of 4,000 gallons per hour, the 400 gal tank would have 10 times turnover and we know about what that would look like (fair water movement but not at all turbulent). But now consider what the current in that 40 gallon sump with 4,000 gallons per hour moving through it will look like. You will be able to visually see the turbulence of the 100 times turnover of that 40 gallon sump. This shows that each body of water in the system must be considered separately as they will be effected based on their individual size.

Thus despite the overall volume of the system... the current in each tank in the system should be calculated separately. But this is only true when considering water movement... as with bio filtration the focal point is how often the full volume of water passes through the bio media in the sump... in which you will need to consider the volume of the entire system...

The good part is... you will want a higher turnover rate for mechanical filtration (enough current to move waste into filter intakes)... where lower turnover rates will be sufficient for the needs of bio filtration... which is exactly what you will get with this type of system...

The trick to making all of this work, will be using a sump container that allows enough volume to allow enough room for discharge when the pump is turned off, typical evaporation and still have a functional depth... Increasing to a 16" x 16â€


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## cholile (Oct 28, 2007)

I certainly recognize the fact that whatever turnover there is within the system it will be nearly double in each tank since each tank accounts for just under half the volume. So that's why it seems like aiming for 5 times in the system and thereby ending up with about 9 times per tank is ideal.

I'm wondering now whether this trash can isn't the perfect size. I found a black (the color I'd want given the tanks/stands/background will all be black) Rubbermaid 41 Qt. Wastebasket, Model RCP 2957 BLA for $8 at Home Depot. http://www.homedepot.com/webapp/wcs/sto ... =100135088

It lists the specifications as follows:
# Assembled Depth (In Inches) : 11.875 In.
# Assembled Height (In Inches) : 20 In.
# Assembled Weight (In LBS) : 1.3
# Assembled Width (In Inches) : 15.25 In.
# Bucket/Tub Capacity : 41 Gal.

I'm not sure what the bucket/tub capacity means, but those dimensions would yield about 15.5 gallons of space in the the trash can. So if I put a mag 7 at the bottom of it and had some other baskets of media just above that then I ought to be able to have it about 1/3 to 1/2 filled with water + media when running and then leave about 7 gallons worth of space at the top.

The problem is that the height is about 2 inches too tall I think for the water to flow from the bottom tank into the trash can.

So, I guess there are two questions.

1. Imagine the height wasn't a problem. Does this sound like it would work? Because of the dimensions I could have the trash can either placed at an angle in the "square" area or move the tanks an inch or two apart thereby creating a 14" x 14" area.

2. If I find a trash can with the same dimensions, but it is significantly taller and I just drill the can and have the pipe placed at the 18" mark of, say, a 24" tall trash can, then would that work?

If either of those sound problematic then I will certainly try to locate a trash can/bin/bucket of some kind that is about 16" x 16" x 18" and place it between the tanks. Of course I want something black so as not to be too distracting.

I imagine I also have to worry about the sump bowing, though it generally wouldn't be filled with too much water except when the system is shut off for water changes and I could drain the trash can first.

In a perfect world I'd have automatic water changes by drilling another hole in the sump for water to drain out (and then the whole worry of water spillage when the tank shuts off would also be removed) but I don't think I will have that option given the locations I have to choose from for placing these tanks.


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## Toby_H (Apr 15, 2005)

I think you are on a much better track now...

I don't think the can you mentioned is perfect and I would keep looking around... but it doesn't sound too bad either... I would continue looking for that perfect 16" x 16" @ 18" can, but keep this one in mind if nothing better is found.

I still queston the maximum drainage rate of the tanks with only a 1" hole drilled in them. You may want to set the bottom tank on the rack and set up a pipe with the same fall angle you intend on using and do an experiment.

The smaller the pump you use... the less the water will build up above the bottom of the drilled hole... therefore the less water will settle into the sump when the pump is turned off... therefore the smaller of a sump you can get away with...

For filtration purposes I agree an actual flow rate of 350~400 gph would be ideal... but going slightly smaller for practical purposes may be necessary. If you do go smaller supplimenting with powerheads and/or HOBs is an option.

I don't think the can being a bit too tall and then drilling it will be an issue... I also do not think that the sump bowing will be problematic. But naturally do not trust my speculation on this. Get the can you plan to use, make any alterations to it you have planned (such as cutting holes) then fill it up in the back yard and leave it overnight to make sure.

Question... what are you doing for filtration on the 15 gal tanks? What are the dimensions of your 15 gal tanks (all glass lists a 24" x 12" x 12" and a 20" x 10" x 18").


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## cholile (Oct 28, 2007)

Thanks Toby. It could be the hole is larger and the bulkhead itself is actually creating a 1" diameter to drain. Obviously this is rather important, but I don't have the tanks next to me at the moment. I'll have to check on that. I purchased them from a fish store that had them set up as part of their system when the store liquidated (real sad. it was a great store). They knew what they were doing so I imagine the holes were "the right" size though obviously I should just measure when I have the chance to see the actual size.

The 15Gs are 24 x 12 x 12. Essentially, they are the 33G tanks cut in half (which, for visual purposes, is obviously important).

The 15G tanks are not drilled and they are each using HOB aquaclears. Long term I expect to use both as grow-out and/or hospital/quarantine tanks.


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