# are undergravel jets overrated?



## brian93 (Sep 20, 2007)

do ugjs really keep debris off the gravel? how do they work exactly?


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## SLIGHTLY STOOPID (Dec 23, 2004)

Some think so Start Here


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## cichlid_junkie (Dec 19, 2005)

They work great if you set them up right. Keeping all the jets pointed towards the filter intake(s) really helps.

I haven't vacuumed my tank in so long I'm not sure where the vac is


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## boredatwork (Sep 14, 2007)

SLIGHTLY STOOPID said:


> Some think so Start Here


That thread was very useful to me at the time.

To answer the question, the concept of UGJ's is to create continuous water flow along the top of the substrate to prevent waste from settling. The flow should be set up in such a way as to guide the waste to the intake of the filtration system thereby keeping any waste from accumulating on the substrate.

My contention was, and still is, that the UGJ setup does not work as advertised and has several inherent flaws. I think UGJ's are a poor solution to a somewhat benign problem. You can read about that in the link, but I think it was in another thread that Mcdaphnia mentioned that he uses powerheads placed directly in the tank instead - which apparently is the technique commonly used in reef tanks. I think this is a much better idea because the system is a lot easier to setup and modify.


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## Stickzula (Sep 14, 2007)

I'm sure that powerheads have their advantage, but I wouldn't trade my UGJ's.


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## Mcdaphnia (Dec 16, 2003)

Something like this works great, but it is sure no DIY or inexpensive solution. http://www.saltycritter.com/wavemakers/ ... avebox.htm
And for about $300 to $950 less, there is this gadget.
http://www.marinedepot.com/ps_ViewItem~ ... 01401.html



Stickzula said:


> I'm sure that powerheads have their advantage, but I wouldn't trade my UGJ's.


Get back to us on that after a while. The big advantage, in today's energy-conscious world, of a power head is lower energy consumption for equal flow. The big, perhaps only, advantage of under-sand jets is in display tanks where concealment of technical aids is paramount.


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## prov356 (Sep 20, 2006)

> Keeping all the jets pointed towards the filter intake(s) really helps.


So, if you blow the detritus to the intakes, it gets drawn right in? How strong are the intakes, meaning 
what's the gph on those? How do you funnel everything right to an intake so it gets drawn in? Most 
intakes only draw something that floats really close to it. Is it a matter of circulating it in the general 
direction so that if it gets blown by often enough it gets taken in at some point?



> I haven't vacuumed my tank in so long I'm not sure where the vac is


But, does that mean there's really nothing in the substrate to vacuum? If you stir the sand, there's no 
sign of any detritus? Nothing gets caught under the edge of rocks or anything else?

Just some burning questions that I've wanted to ask proponents of UGJ's.


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## cichlid_junkie (Dec 19, 2005)

> So, if you blow the detritus to the intakes, it gets drawn right in? How strong are the intakes, meaning what's the gph on those? How do you funnel everything right to an intake so it gets drawn in? Most intakes only draw something that floats really close to it. Is it a matter of circulating it in the general direction so that if it gets blown by often enough it gets taken in at some point?


In my 75g tank I have a 900 gph Eheim pump running my UGJ (actual flow rate is a lot less than that). Along with that I have a Eheim 2028 canister filter. I think you would agree that I have a lot of filtration in there. I would guess that the water is cycling about 12 times an hour. I also have a really good flow pattern through out my tank. Right now my tank is about as dirty as it every gets (no water change for 2 weeks! I was on vacation last weekend and didn't change the water - just added some of that nitraband stuff to hold me over till this weekend  ). Even though it's been a while the substrate is still pretty clean.



> But, does that mean there's really nothing in the substrate to vacuum? If you stir the sand, there's no sign of any detritus? Nothing gets caught under the edge of rocks or anything else?


Whenever I do a water change I stir it up quiet a bit just leveling the substrate back out from my fishes relentless digging. They love that aragonite. Within an hour the water is crystal clear again and the substrate is clean. The only problem I have with detritus is from this. It fills up with the "stuff" and I have to shake it out every couple of water changes. Even then, after I shake it out, it all flows to the UGJ filter within an hour.

By the way, for a filter I use a foot long piece of 3/4" PVC with lots of slits cut in it and wrapped with four layers of walmart batting. Lots of surface area to hold the detritus. It gets replaced every water change. It's really dirty now after 2 weeks of running! Oh yeah, it only runs during the day, about 12 hours. It's on a timer, lets the fishies sleep better at night :zz: Only my canister runs all of the time.


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## boredatwork (Sep 14, 2007)

prov356 said:


> I haven't vacuumed my tank in so long I'm not sure where the vac is
> 
> But, does that mean there's really nothing in the substrate to vacuum? If you stir the sand, there's no
> sign of any detritus? Nothing gets caught under the edge of rocks or anything else?
> ...


First off, why do they put the Report button right next to the Quote button. I can't tell you how many times I click the wrong one.

Secondly, I believe the problem is subjectivity. I started to understand this when I see threads where people say something is "quiet". Essentially saying something is quiet it is a useless description. I think its possible the same thing is going on when people talk about UGJ's. What does "clean" mean. I think my tank is filthy, but I am guessing to the average person it is pretty clean. Clean for me means there is no waste in the tank, substrate, or water.

I don't want to re-hash everything that was discussed in the thread that was linked but I used UGJ's for several months, and I worked hard to make them work. I went through two total redesigns. The problems I found were exactly the ones prov is getting at. The jets obviously easily keep waste off the substrate but that does not mean the waste ends up in the filter. Just because you don't see it doesn't mean its gone. The UGJ system is effective at creating water flow, but it cannot be effective at removing waste from the tank. To do that it needs to work in concert with the filtration system. If they filter intake (cannister, HOB, or overflow) cannot suck in the floating waste then all you have is a system with poop floating around. In my case I watch as poop flowed right past the filter intake. If you stick your hand next to the filter intake you will notice that there is not a lot of suction. So unless the jets are perfectly tuned to push poop to the filter intake and make it stop there long enough so it can get sucked in the UGJ is not going to work.

So the question is, if the poop is not accumulating on my substrate then it must be in the filter right? Well I am saying it does not get sucked up by the filter. Then where does it go? In my case I had several rock piles along the back of the tank. After several weeks of running UGJ's and then taking down some of the rick piles I found out where all the poop went. The rocks were way more effective at catching suspended poop than the filter was.

Another trick part is that waste, both food and poop, that sits on the substrate will break down and start to disintegrate into finer particles. A piece of poop or uneaten food will basically turn to mush after a few days/weeks. Thats why I think some people think that when they disturb the sand they don't see any poop. But the water will get cloudy from all of the disintegrated waste. So technically the poop is still there - just not in the form you were expecting.

Another problem with UGJ's other than the performance (or lack thereof) is that of added noise and temperature pollution from the pumps. The temperature in my tank dropped 8 degrees when I shut down the UGJ's. In the middle of summer that becomes a big deal. Don't even get me started on noisy pumps.

Most people intend to use UGj's are an alternative to vacuuming. The biggest problem with this is the obvious. When you vacuum your substrate you are removing the waste from the system - the system being the tank and filtration. Even if a UGJ did work the waste is still in the filter. And most people do not clean their filter very often. So they only possible use of UGJ's can be cosmetic.

I will stop here. I probably have another 5-10 points to make but I can feel my blood pressure rising. Technically, in response to the OP, they do keep waste of the gravel - bu that doesnt mean the waste is removed from the tank.

The main point is that UGJ's are advertised as the greatest invention in fishtanking in the recent era. I would tend to believe that the hype is MUCH bigger than the performance.


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## cichlid_junkie (Dec 19, 2005)

Boredatwork, a rock pile would be a challenge to keep clean. Maybe you could jet water at it to blow the detritus out from the cracks in pile or maybe put a bubbler under the center of the pile. Either way you have to get some kind of flow there. It's either that or do it the manual way and take it apart every once in a while to clean it. Hey, how's this for an idea, fill the cracks with substrate, that would keep the detritus out. 8)

Anyways, there are just some things you can put in a tank that are higher maintenance items. If you want a low maintenance tank it looks like a simple rock pile might pose some hidden challenges.



> Another trick part is that waste, both food and poop... So technically the poop is still there - just not in the form you were expecting... added noise and temperature pollution from the pumps.... Most people intend to use UGJs are an alternative to vacuuming... most people do not clean their filter very often. So they only possible use of UGJ's can be cosmetic.


 :? 
All of your points about what's wrong with UGJ's are exactly why you have to "design" a system that works for you. I hope you were not under the impression that a UGJ would magically remove the detritus from tank. In a properly designed system the detritus ends up in the filter and not on the where you have to look at it on the substrate, and yes you do have to change that filter every time you would instead be vacuuming. What is your water turnover rate in your tank? 10x per hour is recommended (750gph in a 75g tank), mine is around 12x. Pump noise - research and find a quiet pump, my Enhiem is very quiet. The pump adds heat - I live in Florida and my pump is out of the tank for just that reason. Also not putting the pump in the tank gave me the opportunity to use it for water changes. Even your rock pile problem could be solved with a little effort.

As an engineer I had a blast designing my system. Designing stuff is what I love to do. As much as I like my current system I still have a bunch of ideas to make it better and that's what makes things like the DYI UGJ so great.

P.S. If I was buying another pump today I wouldn't by an Enhiem, European pipe sizes are very hard to work with in the USA.


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## fishEH (Sep 15, 2008)

After a lot of thought on my new tank I have decided against a UGJ. In fact, I have gone the opposite direction on my 75 gallon. Its houses a 5" Oscar and a Southern Painted turtle. They are soooo messy. I have put a Hydor powerhead aimed directly at my filter intake. This is not to direct detritus towards the intake but to blow it past the intake so it settles on the bottom. This way my intake does not load up with debris and inhibit filter performance.


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## prov356 (Sep 20, 2006)

fishEH said:


> After a lot of thought on my new tank I have decided against a UGJ. In fact, I have gone the opposite direction on my 75 gallon. Its houses a 5" Oscar and a Southern Painted turtle. They are soooo messy. I have put a Hydor powerhead aimed directly at my filter intake. This is not to direct detritus towards the intake but to blow it past the intake so it settles on the bottom. This way my intake does not load up with debris and inhibit filter performance.


That's a good design. Use the filter for biofiltration and vacuum the bottom during partial water 
changes. That's your mechanical filtration. I like it. :thumb: Probably a lot easier than cracking open 
the filter to clean or dealing with a severe slowing down of the filter gph. Gotta do the water changes 
anyway.


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## brian93 (Sep 20, 2007)

Maybe its not the concept of ugj's that are the problem. maybe its the person utilizing the concept (no offense). i havent built one yet, and i probably wont get it right the first time, but obviously it has worked for some people and it hasnt for others. the people who swear by them just might have figured the whole thing out, and some havent. the people who like using ugj's maybe should try to explain how they got theres to work.

making one of these work sounds like christmas but better; you dont have to vacum the sand (to a certian degree). it might be kind of like making a perpetual motion machine:impossible.


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## Mcdaphnia (Dec 16, 2003)

brian93 said:


> Maybe its not the concept of ugj's that are the problem. maybe its the person utilizing the concept (no offense). i havent built one yet, and i probably wont get it right the first time, but obviously it has worked for some people and it hasnt for others. the people who swear by them just might have figured the whole thing out, and some havent. the people who like using ugj's maybe should try to explain how they got theres to work.
> 
> making one of these work sounds like christmas but better; you dont have to vacum the sand (to a certian degree). it might be kind of like making a perpetual motion machine:impossible.


Best description of a UGJ I've heard.


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## prov356 (Sep 20, 2006)

> people who like using ugj's maybe should try to explain how they got theres to work


I'd like to see that too. One that eliminates vacuuming, which is the claim that I question. I know many designs can help, so I don't need to see those.



> I hope you were not under the impression that a UGJ would magically remove the detritus from tank


We're not that naive, no. Just questioning the claims that it makes vacuuming the substrate unnecessary. And those claims have been thrown around quite a bit.



> In a properly designed system the detritus ends up in the filter and not on the where you have to look at it on the substrate


All of it? Show us that design, please! We're begging now.


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## boredatwork (Sep 14, 2007)

brian93 said:


> Maybe its not the concept of ugj's that are the problem. maybe its the person utilizing the concept (no offense). i havent built one yet, and i probably wont get it right the first time, but obviously it has worked for some people and it hasnt for others. the people who swear by them just might have figured the whole thing out, and some havent. the people who like using ugj's maybe should try to explain how they got theres to work.


OK I used to think that. It certainly is a subjective opinion but I like to think I am not an idiot.

I would put your theory a little differently. Maybe all UGJ's work the same but either through ignorance or differing expectations some people view their effectiveness differently. If I want to believe there is no poop in my tank then thats what I will believe. Or if I am satisfied with the performance regardless of how "good" it is then I am happy with it.

And I will say that my expectation was to never have to vacuum my gravel ever again because thats what people say ... all the time! So when people make those comments I feel obliged to say that it is not true.

The problem with an UGJ system is not flow. My UGJ had lots of flow - plenty of flow. It was not unable to move waste around the tank. It was very good at that. I have said this many times - I literally watched a pieces of poop float around my tank several times never once touching the sand. After about 3-5 trips around the tank is got stuck behind a rock. The point is that rock, corners, plants, etc, are much more effective at capturing the floating poop than the filter intake is. Therein lies the problem. I don't have an issue with the UGJ being able to create enough water flow.

And as far as rocks go if they are a limitation on UGJs working then they will not work for most tanks I have seen. If you have an Mbuna setup with large rock piles there is absolutely no way possible to create water flock in every rock crevice, and even then I will still say that the poop will get stuck in the rocks.



> In a properly designed system the detritus ends up in the filter and not on the where you have to look at it on the substrate


I actually said that an UGJ system will accomplish this - but only because poop behind rocks is out of sight. It does not remove it from the system - at best it can remove it from the tank, but even then I think is a stretch to make that claim. Vacuuming will remove it from the system, not just the tank.

As far as tweaking an UGJ system I think that is it's biggest flaw. I did it twice and it was a traumatic event both times. This is why I think using powerheads directly in the tank is a much better idea. In all honesty I am not sure why a UGJ system would be preferred over this method anyway.


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## brian93 (Sep 20, 2007)

well if you only used powerheads to keep stuff off the sand, how many would you buy?


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## Mcdaphnia (Dec 16, 2003)

brian93 said:


> well if you only used powerheads to keep stuff off the sand, how many would you buy?


 One Mag 18 per tank worked for me. Although when one conked out and I replaced it with a larger Chinese pump, that worked too. The tanks were both eight feet long, one 520, the smaller one 250. I had to create a device to convert the flow from a small volume of water moving rapidly to a large volume moving slow enough not to travel eight feet across the bottom of the tank and then up 42" and spill out over the opposite end of the tank. I had to do this also because I didn't want to rip the scales off my fish. opcorn:


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## brian93 (Sep 20, 2007)

WOW. that some heavy duty hardware...


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## wheatbackdigger (May 11, 2008)

Best decision I made was to remove the UGJ from my 150 and install a full length spraybar across the back of the tank. No more excessive heat or humming noise. Less equipment in the tank to hide and the spraybar keeps excess waste suspened until it reaches the intakes, with the benefit of tons of surface aggitation. A quick five minute vacuum with the weekly water changes gets any leftover waste. UGJ don't impress me much


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## dittobaker (Sep 15, 2008)

I have a *hybrid* version (for lack of a better term) of the UGJ's in my 75 gal tank. I have the "plumbing" underneath the gravel, but instead of mounting power heads to it, I have my canister output line connected to it. Here are some comments about my setup.

1) I have 3 branches of the plumbing underneath my gravel. Plumbing is 3/8" (if I recall correctly). At the end of each branch, I have a 45 degree elbow blowing up, with a cap on the end. I've drilled a small hole in the end of the cap. I've done this instead of simply crimping the end of the PVC like some suggest. Since my setup is powered by my canister filter, the flow is lower. The smaller holes will allow for quicker movement. The caps are not glued in place and can be removed if I ever need to clean out the pipes.

2) I also have eggcrate under my gravel. I cut out a pattern in the eggcrate to match the pattern of my plumbing. This allows the plumbing to sit much lower in the gravel and keep it hidden. If you see my setup, you would never know there's pipes in there if you didn't notice the water swirling.

2) Powering my UGJ's with my canister filter instead of a power head removes the issue of added heat and noise.

3) The first reason for my design is to help remove "dead zones" in the water, where there is little circulation. I also have a HOB filter which keeps the top half of the tank circulating nicely, but I wanted something to keep the bottom circulating as well.

4) My rock setup has very large caves underneath the bottom of the rock between the rock and the gravel. Without the UGJ's I would not be able to clean under these rocks when I vacuumed the gravel (yes, I still vacuum). The UGJ's spray into these bottom caverns to help circulate debis out of these hard to reach areas into areas easier to clean.

So, what my hybrid setup does:
- Helps remove dead spots in the water
- Helps keep debris from building up in hard to reach areas
- Eliminates noise and heat polution caused by powerheads
- Eliminates visual distractors such as powerheads and spray bars

What my hybrid setup does NOT do:
- Eliminate the need for gravel vacuuming
- Solve world hunger

I've had this setup for 8 months now and have not had one problem with it. It seems to meet my objectives quite nicely.

If anyone would like help is setting up a hybrid like this, then let me know.


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## boredatwork (Sep 14, 2007)

dittobaker said:


> What my hybrid setup does NOT do:
> - Solve world hunger


Then I just don't see the advantage!

In all seriousness, given your expectations, then I think any UGJ would be sufficient. Certainly using the cannister output instead of additional pumps solves some problems, but there are a lot of opinions out there as to why using a canister to power a UGJ is not a good idea.

Using small powerheads or hydor pumps withoutu all of the plumbing and eggcrate seems to me to offer a lot more flexibilty and simplicity while still achieving all of the objectives you mentioned. Thats my plan anyway.

It has been well documented why I gave up on UGJ's. I believe that they are fundamental flaws and over-the-top expectations. To me the flaws are fundamental enough that any variation on them will not be worth it. And when the expectations are dialed back to be realistic, then I think you undercut any justification for UGJ's in the first place. Why add all the extra complexity of the UGJ instead of just one or two small pumps to create flow?

My new plan combines my failed DIY sump attempt and failed UGJ attempt into one "perfect" solution. (Although based on past experiences it will only be perfect until I actually build it - then I will hate it). The only reason I wanted a sump was to hide the heaters, and when I had the UGJ's they created really good flow. So now I am going to add two powerheads in conjunction with my cannister to create water flow , and I am going to use one of the powerheads to hook up an inline heater and UV sterilizer. So I will get the flow I want, the heaters are taken out of the tank, I can setup the powerheads to increase surface agitation, and all without any plumbing in the tank. The beauty of this is that it is as simple as it gets and it is easy to reconfigure.


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