Need advice on reducing Nitrate

This is my first post and I've taken the name ThickAsaBrick because I feel that way when trying to solve aquarium problems like my current Nitrate situation.

The nitrates in my tanks seem to be out-of-control and it's driving me nuts because it doesn't make sense chemically. The ammonia and nitrites are fine but I've had to do water changes (50-60%) three days in a row because the nitrates have been from 40 to 80 ppm (though I admit I am very frustrated trying to tell colors apart on the API Nitrate test scale). The tanks each have only one 6-8 month old axolotl living in them (one is 10 gal and the larger Axie has a 20 gal. Both have canister filters with a sponge on the intake line and flow rate about 79GPH.

Since the tanks cycled I've had to do changes due to nitrates about every 3 days. My axies are chunky so I know they are eating too much and probably producing extra waste but I started cutting back on their food before this spike so that doesn't seem to make sense either.

Aside from plants what can I do to control Nitrates better? I am leery of chemical solutions since they are usually intended for use with fish rather than amphibians. I know plants would help me control nitrates but I don't have any because I haven't been able to buy clean plants. Where do you get plants that you can be sure don't have some pests coming in with them? Even the certified pest free plants I bought at Petco individually sealed had some kind of organisms growing on the leaves.

For testing your nitrate are you using strips or a liquid reagent? If strips, switch to liquid. If liquid, read and follow the directions exactly as this could lead to a misreading.

Have you tested your tap water for high nitrates? Next water change test your aged water.

Check for uneaten food or anything decomposing inside your aquarium.

As for a solution to lowering nitrates between water changes, plants would be the obvious choice. Duckweed and elodea are two varieties of plants which excel in this area. If you are looking for a product to do the filtering, you can read into Purigen. I've never used chemical filtering so it's outside my experience.

You can quarantine plants before you add them to your tanks - the most likely invader is snails, and TBH my axies eat the small pond snails and solve their own problems.

I second Elise, check your tap water for nitrates, give the tank a good once over for waste and uneaten food.

What substrate do you have? You could have food or waste trapped in whatever you've got, it might be worth checking that too.

Thanks for the suggestions and you both were on target. Last night we took the largest axie, Feynman from his tank did a very complete cleaning of everything in the tank to include substrate (black sand) and even the filter lines. This included a huge ~85-90% water change. We put him back and he seemed more active but my wife wanted to check levels to see the new baseline. The Nitrates were sitting at 30ppm.

This left me only 2 possibilities, the test kit (API liquid test) was bad or the water source had Nitrates coming in. I tested the new water and that was the problem. It was sitting about 30 brand new. Amazingly, I've been using Zephyrhills Spring water because I had an affordable source and didn't trust my tap water. We have done this since we got them a while ago and I know the spring water was 0 ammonia, nitrite and nitrate when we started because I was measuring daily while cycling.

So, the ultimate newbie question, what do the experts here do for water? Tap water treated with Seachem Prime to dechlorinate? My tap water does test at 0 Nitrate and I downloaded a city report on the water in my neighborhood (Chlorine 1.7 ppm, Sodium 18 ppm, Fluoride 0.7 ppm, Barium 0.017 ppm, Copper 0.32 ppm, Lead 1.3 ppb, Arsenic 0.255 ppb, HAA5 32.3 ppb, TTHM 53.5 ppb). That seems okay, Some nearby areas have Asbestos, Dalapon, pestacides, and even radioactive Radium in their lists.

Sounds about right with the water report! I was surprised to find things like cyanide, strychnine, lead, mercury and arsenic in my water report.

(scientific jargon alert) Dechlorinators all contain sodium thiosulfate. This is a compound that works by binding (chelating) to all the nasty stuff found in tap water. It effectively neutralises chlorine and other halides (flourine, iodine) and metals (lead, copper, silver, arsenic). Medically it is also used to treat cyanide poisoning, and commercially it is part of the old-fashioned photo developing process (in the days we used silver nitrate film!).
So any dechlorinator will remove chlorine and other nasties from your tap water and make it safe for use in an aquarium - no need for expensive bottled stuff.

If it's any consolation your water report looks about the same as mine.

I'm glad you found the source. That copper level in your report struck me as high. Hardness probably would play a role in the toxicity.

In this document which lists drug compounds for amphibians, it states that a two minute, 1ppm copper sulfate dip would treat parasites. Correct me if I'm wrong but copper levels at .36ppm would be fairly toxic to an axolotl.

A brief search found this only slightly relevant excerpt:
(Source).


I'm having a hard time finding an exact level of copper which would be toxic to amphibians or axolotls.