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RE: Undergravel filters and water flow

math-only aquarium — Tue, 01 Jul 2008 18:26:25 GMT

P.S. Most of my tests indicate a turnover of 10-20 to be quite beneficial except in cases were the fish cannot handle it (breeding tanks, tanks for species with long fins or obtrusive body modifications, or some plant tanks depending on oxygen-carbon dioxide balance).

RE: Undergravel filters and water flow

math-only aquarium — Tue, 01 Jul 2008 18:23:04 GMT

Interesting,

I have been playing around with different waste production theories myself and have also found nitrate levels to be somewhat poor with regard to predicting failure points and high stress points (not that I'm recommending an adbandoment of their consideration altogether, mind you). Instead, I, being the math geek I am, found that using a remaining waste index to be a far better prediction of danger levels. The basic theory is that every chemical that comes in contact with your tank's water is never 100% removed (although possibly very close to 100%) and thus some remains. This means that cleaning agents that wafted across the room, chemicals from the building under construction, fumes from the BBQ next door, and all other manner of chemicals that are water soluble will be present in minute, but ever increasing, levels. Once these wastes accumulate to a critical level, they will have adversely affected the fishs' immune systems and subsequently be reasponsible for the majority of system failures.

Just a theory, of course, but I'm finding it to be a better model than the MAT equation.

MOA

RE: Undergravel filters and water flow

princessotfu — Tue, 01 Jul 2008 15:04:25 GMT

It is slightly off topic, but a response to your theory on nitrates, David. I've read a few studies by Diana Walstad and others, and it seems like you're partially correct. Nitrate tolerances vary widely between species, but most fish won't experience "real" symptoms from nitrates until they hit about the 150-200ppm range. Some not until you hit the 1000ppm range. However, all the studies say that this does not mean your fish aren't experiencing physical stress at lower nitrate levels, just that it isn't enough to manifest itself as visible symptoms. That's the paraphrased version, anyway.

RE: Undergravel filters and water flow

David Lass — Tue, 01 Jul 2008 10:44:39 GMT

I'm in the process of testing a system for my FAMA column "In The Fishroom" that is a reverse flow UG with two side "towers" that have "bioballs" with centers that harbor anoxic bacteria, which break down nitrates. I've had this thing going for better than two months now, piles of fish, all kinds of plants, and the water is crystal clear, the plants are going great, haven't lost a fish. The idea behind this product is that using it makes water changes unnecesary -- which makes me nervous to begin with. But I am really trying to test it, and so I have not done anything but top it off with water. Have never had any ammonia or nitrite (used their bio starter, which worked great), and the nitrates seem to have settled down in the 40 -- 60 range. I know that many of you will think that is way too high for the nitrates, but the more I test and play with things the more I am becoming convinced that nitrates are only a problem if they are really off the chart, or if you introduce fish that have come from 0 nitrates into a tank with high nitrates.

Anyway, the reverse flow ug solves the problem of sucking everything down into the gravel and below the ug plate. All you have to do to run it that way is to attach powerheads to the lift tubes.

RE: Undergravel filters and water flow

tnemaloney — Tue, 01 Jul 2008 07:10:21 GMT

i started out with an ugf in my 55, and i thought it was great till i changed it out and realized how much waist was stuck under it, yuck.. now i have sand substrate and the waste sits on top. and as for flow i use 2 power heads 1 at each end of the tank facing the filter, it seems to be working great and i am very happy with the setup

RE: Undergravel filters and water flow

dogdoc91 — Mon, 30 Jun 2008 09:19:11 GMT

Planted tanks like lots of water turnover. I have heard recommendations of 10 times the tank volume per hour. So you will get your water movement and oxygenation with your filter. Meaning the filter flow will agitate the surface of the water where the oxygen exchange happens. You don't have to have airstones and if you are planning on using CO2 injection you don't want an airstone. It just drives off the CO2.

RE: Undergravel filters and water flow

Bremmon — Mon, 30 Jun 2008 08:12:12 GMT

Thanks for everyone's replies.

I am in no way biased one way or the other but it totally makes sense that plants would clog it up so an undergravel filter does not sound like the way to go. My second Saltwater tank didn't have an UGF and I had no issues because of it.

What about flow thought? I know that flow in a tank helps Oxygen exchange so it is good to have the water turning over consistently.

In the saltwater world, especially a reef tank, you need lots and lots of flow. But what about in the Freshwater world? How much flow is recommended?

I imagine that you don't have to have air stones necessarily like we did in the old days though I could be wrong on that.

Thanks.

RE: Undergravel filters and water flow

painthorse77 — Sun, 29 Jun 2008 16:12:03 GMT

I have had a UGF with a moderately planted tank before. The plants rooted under the grate and grow very well (exceptionally the Banana plant). I took it out when I had to move the tank. If you are going to have a densely planted tank I would advice against it because the roots of the plants will clog the slits in the grate.

RE: Undergravel filters and water flow

math-only aquarium — Sat, 28 Jun 2008 18:06:49 GMT

Hmm,

If you still like the idea of undergravel filtration but want something that is better for plants, you might consider a "carpet" plenum. A carpet plenum is essentially just some UGF plates without the uplift tubes that are covered with 1/4-1/2" of fiber floss or other such medium and then covered with substrate. The advantage is that having a carpet plenum keeps anareobic zones from forming in relatively deep substrate (like that found in planted tanks) so long as the flow rate of of the circulation pumps is fairly high (3-8 cycles per hour).

No less, such a system is probably not the most convenient for your case. As such, a canister system might be the better way to go.

MOA

RE: Undergravel filters and water flow

Hailey — Sat, 28 Jun 2008 06:31:06 GMT

I agree that using one in a planted tank would pobably lead to a lot of headaches, especially if it is to be heavily planted. They would probably be fine if you were just going to have a plant here and there and call it a planted tank, but if you're going all out with the plants, I'd get a different kind of filter (a canister is probably best for this application).

RE: Undergravel filters and water flow

dogdoc91 — Fri, 27 Jun 2008 13:32:03 GMT

I have to say I also think UGF and plants are a bad idea. Plants are going to attach their roots to all of the nooks and crannies in the UGF and block the flow. Also you may want a deeper gravel bed. I have about 2 inches of Eco-complete plant substrate with 1 inch of regular gravel on top of that. It makes anchoring your plants easier if you have a deeper bed. Then they don't get loose and go floating around after you plant them.

RE: Undergravel filters and water flow

Lumberjack — Fri, 27 Jun 2008 10:04:51 GMT

UGF and planted tanks have never really gone well together.

RE: Undergravel filters and water flow

math-only aquarium — Fri, 27 Jun 2008 08:07:07 GMT

Hello Bremmon,

First of all, I tend to be biased in that over 95% of my personal aquarium use UGFs, so take what I have to say under consideration.

1) The current thoughts on UGFs are varied. I, personally, love them because they are simple, effective, and inexpensive to maintain. Others, however, often cite clogging and below-bed waste accumulation as being major problems with UGF systems. Other people also accuse them of being inappropriate for planted tanks.

2) Flow is actually the deciding factor when it comes to UGF systems. In my experience, UGFs will work just fine so long as your turnover rate is at least five cycles per hour. This means that the gph of your UGF powerheads should be five times the capacity of your tank (275 gph in your case). Most people who have problems with UGFs either have too small a flow rate or do not regularly siphon the gravel (once a week is best).

Lastly, remember that a UGF is a biological filter in the strictest sense--you don't have room to make dumb mistakes like not cycling your tank or skipping cleaning times.

MOA

Undergravel filters and water flow

Bremmon — Fri, 27 Jun 2008 07:50:00 GMT

I have a 55 gallon tank that I will be setting up. It will be a planted tank with tropical fish. I plan on having about 2 inches of substrate, probably Flourite.

My questions are these:

1) What are the current thoughts on undergravel filters?

I had one for a saltwater tank many years ago and it worked great. Lately, the saltwater community stays away from undergravel filters for many good reasons.

I don't hear the same negativity towards undergravel filters in the freshwater forums.

2) How much flow should there be in a freshwater aquarium? I imagine there is alot of flow if you use an undergravel filter.

Thanks in advance.