Is fish urine the largest source of ammonia?

[vfc]

Has anyone come across a study of the relative sources of ammonia in a fish tank? One that has a break down by percentage; e.g., urine-65%, uncollected solid waste-20%, and uncollected uneaten food-15%?

The reason I ask is that in my bare bottom tank, I have been sucking out the solid waste every few days, have no uneaten food as everyone of the NLS pellets are consumed before hitting the bottom, and the HOB filters clean, yet I still get about the same nitrate reading after a week when the same fish were in a tank that had gravel and I did not vacuum off the solid waste.

If urine is the overwhelming source of ammonia, then adding additional (and more powerful) filters to suck up solid waste, has very limited benefit. Your stocking level is dictated almost exclusively by how often you change your water.

 

[mgk]

its probably urine and gills that put out the most.

 

[Madding]

Depending on your type of filter and the media involved, you should be able to deal with the ammonia produced by non-solid waste sources, even urine.

 

[vfc]

Madding,
I understand. My point is that there are a lot of post regarding the benefits of over-filtration (not necessarily the same as over circulation) with the primary benefit being the removal of solid waste. But if most all of the ammonia that is being converted to nitrate is from urine, there is really no need to over filter. The key word being "over". As long as you have enough BB to keep up with the ammonia to nitrate conversion, there would be no benefit to mega filtration.

BTW - I have a bare-bottom 125G being filtered by an AC110 and TetraTec 300 (6x turnover). Those two filters have been able to maintain 0-ammonia and nitrite for a stock of 4x5" Frontosa, 6" catfish, 4" Titanium Flowerhorn, and 3" Gold Nuget pleco.

 

[blackghostuk]

Most ammonia is excreted through the gills, as and when it is produced, on a slow, steady 'trickle' basis, so filters get a constant trace supply. Not much, by comparison, is excreted in urine. Fish cannot convert it to a safer compound like urea or uric acid for storage in urine, so it needs to be excreted as soon as possible.

 

[bob965]

The general consensus is that the solid waste will decay and contribute to ammonia whether it's sitting on the bottom, or stuck in the filter. Your observations seem contrary to this. Maybe nobody has bothered to test it. You should set up a controlled experiment that examines the buildup of nitrate with the presence of fish poop as well as uneaten fish food and post your results here.

 

[vfc]

bob965,
I was trying to justify the purchase of a FX5 canister. My plan was to vacuum the solid waste off the bottom every day or two to simulate the FX5 filter sucking it up. However, I was a bit surprised to see that my nitrates climbed to about the same level each week before the water change.

Now I have held off the FX5 purchase. I don't want to waste money on over-filtration if there are no real benefits.

 

[blackghostuk]

Solid waste will only contribute to nitrates if there is undigested protein in it, as this is where the ammonia comes from. If your fish are good digesters, and the food is easily digestible, there wont be much undigested protein in the poop. If you have no measurable ammonia or nitrites, you have sufficient filtration. As the load increases, you will need more filtration IF your current filter doesnt have enough free surface area for bacterial expansion.

I think the removal of solid waste has more to do with reducing oxygen usage by heterotrophic bacteria than limiting nitrate production.

Also since ammonia comes from protein breakdown, the higher the protein content of the food, the more nitrates will be produced.

 

[Crispy]

Very interesting thread guys... subscribed...

 

[vfc]

blackghostuk,
I feed the fish almost exclusively NLS 3mm pellets. The protein content is high, but maybe the food is easily digestible (like the company claims) and very little undigested protein is ending up in the pooh.

What I also find interesting it that I have enough BB to support the fish bio-load with just two HOB filters.

The tank is bare bottom, so there is no substrate to boost the BB count. There are also not a lot of ornaments for BB to colonize on. Apparently the bag of Bio-Max that came with the AC110 and the bio-sponge inside the TetraTec 300 is supporting a robust BB colony.

I am now thinking that maybe I will just add a power head for more water circulation rather than spend the money on a FX5.