Why do my nitrates keep going up?

[Nola70115]

I don't even have any fish. I'm waiting to add them until l get this under control. I've got 3 hermit crabs, 4 snails (3 of them carnivores), a gorilla crab that's going back to the beach as soon as I catch him, a bunch of stomatellas, and a couple of good-sized bristle worms.

Specs: 7 month old 20 gallon tank, 15 lbs LR, 2" sand bed, Tunze 9004 skimmer, Fluval 425 gph power head, Fluval 206 canister filter running biomax rings, Chemipure Elite, and a polishing pad.

Nitrate 50+
Nitrite .05
Salinity 1.024
Ph 8.2
Alk 6
Ammonia 0
Temp 80

Nitrates haven't been below 40 as long as I've been testing. I've been doing 10% water changes 1x weekly when I clean the canister. Water comes from an ultrapure system at a university biomedical lab. I did start with tap water treated with drops but that was months ago, and the tap water tests negative for nitrates.

I feed the hermits a sliver of fish or green algae pellet every couple of days. The snails steal the fish from the hermits within a few minutes (those snails are fast) so there's no food rotting. There's a light dusting of brown diatoms on the glass and sand, some red hair algae growing on a coral skeleton, and the extra shells lying around for the hermits are black with diatoms.

So, where on earth are these nitrates coming from? started dosing with 1cc of vodka about a week ago, and so far nitrates have gone up from 40 to 50. I don't have a sump but I'm going to try some chaeto in a container in the DT. Any other ideas?

Shell with black diatoms

Coralline growth

 

[Mishri]

nitrogen cycle.. ammonia gets converted to nitrite, nitrite into nitrate.. then.. if you don't have anything to consume it, nitrate just builds.. so yep, cheato or other algae can help control the nitrate by consuming it.

you might want to consider removing everything from the canister filter except the chemipure elite.. it could be trapping waste and decomposing instead of getting grabbed by your skimmer.

I'm also not sure if carbon dosing will be effective without a better skimmer...

other options are GFO reactor...

 

[mcgyvr]

other options are GFO reactor...

If phosphates were an issue that would be one option..
It won't do anything for nitrates though..

You should ditch the canister filter completely IMO..

 

[organism]

Nitrates haven't been below 40 as long as I've been testing. I've been doing 10% water changes 1x weekly when I clean the canister.

That's why.

When you have high nitrates and you want them to get lower you need to do a realistic water change. 10% water change guarantees your nitrates stay high, imo in a 20 gallon even your normal water changes should be 5 gallons. I do 15 gallon water changes in my 34 gallon AIO every 2 weeks if that gives you an idea. Without a sump you must do larger water changes as well.

Try changing 10-15 gallons every other day for a week which will get your nitrates down to 5-10, then stick to weekly 5 gallon water changes. imo 2 15 gallon water changes in 2 days will fix it fast.

Fluval 206 canister filter running biomax rings

This is likely where they are coming from unless you are cleaning it once a week. By cleaning I mean removing the rings, cleaning them, taking out all of the detritus in the filter and cleaning it in the sink, and replacing the polishing pad so that there is no detritus left behind. Personally I wouldn't use a canister filter unless it was running media with denitrifying properties, which I'm pretty sure is only Siporax or Matrix. The media you have now just creates nitrates.

 

[Nola70115]

Thanks, this is helpful. I have been cleaning the canister weekly. It was a gift from my husband and I don't want to hurt his feelings by not using it. :uhoh3: I could take out the media though. The tubing in particular is really hard to get clean.

The Tunze 9004 isn't enough for a 20g tank? I thought it was pretty well reviewed. It's nice that it's really quiet. I had a HOB skimmer briefly that was incredibly loud and produced nothing. The Tunze gets a pretty consistent, albeit watery, skimmate.

 

[HaKs310]

Nola, on a tank this small I would depend heavily on the biological filtration offered via the live rock and good husbandry to keep nitrates under 5. You can still use the canister filter here and there with some filter floss, carbon, chemipure and what have you to polish the water. As far as the skimmer, it looks like it is perfectly rated to handle your size tank and it will not hurt to keep running.

 

[Lsufan]

Did u start with new live rock & sand or did u get it from someone else?

Being u don't have any fish or corals I would do a couple big water changes in a row. That's the only way to lower them quickly. I would change 10 gallons one day then do the same thing the next day. Get them down then see if they stay down or rise back up to 40 or 50 ppm. If they raise again then u know u have a issue that needs to be figured out, whether it be the source of your live rock or the canister. Ten percent water changes once a week isn't going to lower nitrates.

 

[jda]

You need the N cycle to finish and it should consume most of the nitrate. The sand should be able to handle most if it. IMO, you cheated this part of the cycle by using the chemipure and other mechanical media. If you started with dry or dead rock, this is also contributing since it is not ready to have anoxic areas - if you got man-made rock, the stuff is solid and most of it is not really capable of lowering nitrate. I would stop the chemipure and other mechanical filtration and wait until they start to go down on their own.

 

[Diana A]

get rid of the biomax rings. I run my two tanks on fluval 406 and fx6. In the canisters are the foams, and BRS carbon....nothing else. I have a HOB skimmer on each tank too. Each tank is bare bottom because I got tired of the sand. Rock: reef ready rock.

 

[Nola70115]

I only added the chemipure at the beginning of February. The LR mostly came from the LFS. I also have a couple of pieces of dry coral skeletons that have been in there for six months and have algae and coralline growing on them. The are two rock fragments that came home from the beach that have some kind of seagrass growing from the rock. The gorilla crabs hitchhiked in on those. The hermit crabs have pretty much eaten the grass up. There are lots of shells and the three big snails from Pensacola sound.

The sand was not live when it went in the tank. After I added the LR, there were a bunch of little bristle worms in the sand, but lately the only worms I see now are big ones in the rock. I don't know where the sand worms went, maybe the snails or gorilla crabs ate them. I also used to have some mini brittle stars and asterina that have gone missing. I've got lots of pods and a couple chiton. It's only a 2" bed, so I don't think it's deep enough to have anaerobic activity that will take care of the nitrate.

It sounds like big water changes are in order.

 

[Mishri]

If phosphates were an issue that would be one option..
It won't do anything for nitrates though..

You should ditch the canister filter completely IMO..

for some reason near the end of my post i started thinking of phosphate solutions... i think it's because i was looking up chemipure elite....