# Filtration Question



## Morpheus (Nov 12, 2008)

I have a 75 gallon acrylic with a built in wet/dry and sump. I can't seem to get the water crystal clear like I can on my 20 long. I think the problem lies in my mechanical filtration. Right now, i use cut to fit filters, and slide them in the compartment right before the water hits the drip tray. I think my problem is too much water is bypassing the filters I am using. See the pic below:










The first compartment on the right is the overflow. I have my heater in there. The compartment to the left of that is where I have my cut to fit filter. I want to switch to the polyfil from Walmart that so many from here have had luck with. How tight should I pack it in there? Do you think it will be effective in this set-up? Thanks for any advice.


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## prov356 (Sep 20, 2006)

You have to experiment and try to strike a balance. I tried the polyfil as a prefilter and didn't like it at all 
because it clogged really quickly and water just backed up over the drip tray. You might consider 
something as simple as a powerhead with a fine sponge intake. You can even put in in the sump. 
Then it does no harm if you don't get to it to clean it occasionally.


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## Morpheus (Nov 12, 2008)

Thanks Tim.

The sump compartment is quite small. I had to find a pump online that would actually fit and provide enough gph. But I had another idea, and a few questions.

The two chambers that house the bio-balls were filled to capacity when I inherited the tank, so basically the drip tray rests directly on them. I can look through the holes in the drip tray and can see the bio-balls touching it. That being said, could I remove some of them (maybe and inch or so) and place the pre-filter material directly on top of the bio-balls? That way anything that went through the drip tray would pass through the pre-filter. My concerns:

1. Would this affect the oxygenation of the water with having it pass through a prefilter before it hits the bio-balls? Or would the dripping off the saturated pre-filter provide the same effect?

2. When I turn my pump off, the back chambers fill with water. If I remove the drip tray, I have bio-balls in the sump, and trust me it's not easy getting my hand down in there. Can I make this change, if I do it quickly, with the pump running? Basically the water from the overflow would be going directly to the bottom of the bio-ball chambers.

3. Returning to the poweread idea you had, the current is pretty strong as it is. And I am not at all familiar with them. It would have to go in the tank, and I'm not quite sure how I would do that.


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## prov356 (Sep 20, 2006)

> 1. Would this affect the oxygenation of the water with having it pass through a prefilter before it hits the bio-balls? Or would the dripping off the saturated pre-filter provide the same effect?


It's oxygenated and re-oxygenated (is that a word??) as it trickles through the biomedia. The only 
problem I see is fitting it tightly enough so water doesn't find a bypass. If you can do that, you're good.



> If I remove the drip tray, I have bio-balls in the sump, and trust me it's not easy getting my hand down in there. Can I make this change, if I do it quickly, with the pump running? Basically the water from the overflow would be going directly to the bottom of the bio-ball chambers.


I'm having a hard time getting this in my mind and that pic is small, but there isn't any harm in 
changing out a prefilter pad while the pump is running.



> . Returning to the poweread idea you had, the current is pretty strong as it is. And I am not at all familiar with them. It would have to go in the tank, and I'm not quite sure how I would do that.


Direct the outflow across the surface of the tank, so all it really does is ripple the surface where 
cichlids don't typically hang out. You can build or buy some type of spray bar attachment to further 
spread out the return. I know, lots of devices now in the tank. Sump, if possible, would've been 
best. If you can get a larger pic or pics of the sump, I may be able to suggest more. Others too. We 
work best with pics.


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## Morpheus (Nov 12, 2008)

Thanks again. This is the basic set-up I have. However, the size shown where the sump is is not nearly as large as shown:










The sump is under the grooved tray. It's about 4" x 5" and I can barely get my hand down in there:


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## Morpheus (Nov 12, 2008)

Maybe bigger pictures will help. Here is how I currently have it set-up:










And here is what I want to do. Basically remove the first inch or so of bio-balls and replace them with more pre-filter:










I tried putting pre-filter in the area marked nothing, but both the compartment where I have my heater and pre-filter started overflowing over the top. So do you think this will work?

ETA: Well they seem to be the same size, lol. Anyways, the polishing pad in the current set-up is only on the last 4" of the drip tray.

Well


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## prov356 (Sep 20, 2006)

So the drip tray would still be there, but on top of the prefitler?

Why does it show water bypassing the bioballs? Does that just handle overflow if the prefilter is clogged?

Can you put the prefilter in the drip tray instead of under so you don't lose biomedia?

I use the blue bonded filter pad in my drip tray.










I added the 3/4" strips around the inside of it about 1/2" from the bottom. This holds the edges of the 
pad down, so there's no bypass.


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## Morpheus (Nov 12, 2008)

Yes, some water does bypass the bio-balls and goes towards the end, which then drops directly into the sump. I am using the the set-up the way I inherited it. My only concern with prefilter directly in the drip tray is that it might not get enough water flow into the drip tray, because the water is not coming from above, but rather flows over the drip tray. I suppose I could drill some more holes in the drip tray, but didn't know if I should since this is the way it came from the factory. I also know I am using a stronger pump than what originally came with the system, so maybe that is part of the issue as well.


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## prov356 (Sep 20, 2006)

Drill enough holes to handle the flow. You want water going through the biomedia, not past it. Look at 
my tray, hundreds of holes. Always ok to improve on a design, so I wouldn't hesitate if I were you. The 
holes are the first line in dispersing the water over all of the media, which is another reason for more 
holes. Then fit your prefilter in the tray and weigh down the edges with something like small stones, 
pieces of acrylic?


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## Morpheus (Nov 12, 2008)

It actually came with a piece of eggcrate. I am assuming that is what it is for, to hold down the pre-filter in the drip tray (it fits snugly over the drip tray). Will definitely drill more holes then. Looks like I got me a little project tonight. Thanks Tim.


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## acrosstic (Mar 24, 2008)

Why don't you just add more prefilter polyfiber where is says "nothing"?


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## acrosstic (Mar 24, 2008)

Also, try using micron filter pads. They get the really fine stuff.


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## Morpheus (Nov 12, 2008)

acrosstic said:


> Why don't you just add more prefilter polyfiber where is says "nothing"?


I tried that, it caused the chambers housing the heater and pre-filter to back up. Thanks though!


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## Morpheus (Nov 12, 2008)

Ok, I'm an idiot. The small particles I have been seeing are not debris at all, but rather tiny, tiny air bubbles from the water returning (I'm assuming). There are tons of them. While not the most appealing thing to look at, I do suppose it is good for the fish.

Trying to put the pre-filter in the drip tray was an abject failure. I couldn't delivery water fast enough to my pump, even after saturating it in tank water. I still haven't drilled the extra holes in the drip tray. Do you really think removing about an inch of bio-balls and replacing with pre-filter will effect the bacteria? The two compartments are 4" front to back, 17" tall and about 30" wide overall, and full to the brim. I think with the water hitting the prefilter from the top, rather than having to go through the entire length of it, I may have better results.


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## jamthoyoung (May 20, 2007)

> The small particles I have been seeing are not debris at all, but rather tiny, tiny air bubbles from the water returning (I'm assuming)


Your return pump might be sucking in air. In my sump, if the water level is low enough, the pump will create a vortex and suck in small amounts of air - causing lots of tiny bubbles. For me I can resolve by topping up the water in the sump.


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## Morpheus (Nov 12, 2008)

You read my mind. I have my tank marked where to fill it to when I do water changes. I mucked things up last night when trying the pre-filter in the drip tray. So I did another water change tonight, filled to the level I usually do. It looks a lot better.

Tim, I think my pump might be too strong, with no way to dial it back. I think that is why I am having issues with the drip tray. My pump is rated for 565 gph at 0 head, and my return is only 4" or so over the pump. So I gotta be pretty close to max gph. The pump that I inherited was only rated at 375 gph. Could this be causing the power with the drip tray? I drilled a bunch more holes with little effect. There is always at least 1/4" of water in the drip tray, and the rest bypasses.


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## prov356 (Sep 20, 2006)

> Tim, I think my pump might be too strong, with no way to dial it back. I think that is why I am having issues with the drip tray. My pump is rated for 565 gph at 0 head, and my return is only 4" or so over the pump. So I gotta be pretty close to max gph. The pump that I inherited was only rated at 375 gph. Could this be causing the power with the drip tray? I drilled a bunch more holes with little effect. There is always at least 1/4" of water in the drip tray, and the rest bypasses.


Your flow rate is not the problem. That's not too much for a 75 gallon. It should work with that flow 
rate, but we may have to tinker a bit.

Does the drip tray handle the flow without the prefilter in it? Sounds and looks the the drip tray is very 
shallow. Even if you can drill enough holes to handle the flow, you'll be cleaning the prefilter often in 
order to keep it from overflowing. And, that may end up being an ok solution for you if it's easily 
accessible. Can you remove the drip tray and get a pic, so I can see it better?

Clogging of the prefilter is always a potential problem no matter where you put it. If it clogs, water will 
have to either bypass or overflow something somewhere. I go through the same thing. When I first 
clean mine, there's barely any water in the tray when operating. If I let it go too long, it'll clog until it 
overflows. That's not unusual. You saw that when you had it in the baffles. You may have to 
eventually settle on a coarser media than you'd like and come up with another way to filter out very 
fine particles. You're a bit limited by the design of the built in. It doesn't give you a lot of flexibility.


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## Morpheus (Nov 12, 2008)

Thanks Tim. I'll take pics tonight and post them.


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## Malawi King (Apr 10, 2009)

that sounds like you should be fine..

but it sounds like u have micro bubbles after your drip tray that are getting sucked in to your return pump then getting recirculated in to your display tank

try adding a spounge or poly after the drip tray and that should greatly reduce the bubbles you have been getting.

here are some links that have excellent info about sumps

http://www.melevsreef.com/
http://reefkeeping.com/issues/2008-01/newbie/index.php


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