Nitrate question

[tymon]

I have always wondered how much nitrate saltwater fish can handle before it starts affecting them? i know it depends on the fish but lets say easy to moderate care level fish? i was just wondering because i have seen some tanks with really high nitrate levels and the fish seem fine?

[thegrun]

I haven't seen any scientific studies on the matter, but keeping your nitrates at or below 30 ppm on a fish only tank would be what I would work towards.

[tymon]

ya mine are always low like 10. I was at one of my LFS yesterday and i had a cup of their water and i decided to test it and the water seemed to be about 80 nitrates which seems like alot. however the fish didnt seem to upset about it. its not the best LFS.

[dzfish17]

I've heard of public aquariums having high nitrates up in the 200ppm range with no ill effects to fish. I've also heard that adult fish can tolerate higher nitrates than juveniles. I'm old school and still believe that high nitrates stress fish out. I agree that under 30 is where I would keep a FO tank.

[MrTuskfish]

A very controversial question. Although I've heard of a few species that react to high nitrates; I really don't think most fish are bothered at all by nitrate at, say, 60-80ppm. Bob Fenner, in "The Conscientious marine Aquarist", talks about about fish being kept with nitrates in the 100's, even 1000's ppm of nitrate with no ill effects. He does add "of course, the lower the better". I have never seen any any real study that says otherwise. However, when nitrates get too high, I think it is the result of general poor husbandry practices (like WCs) and would expect other problems that would harm the fish. In my FOWLR tanks, I keep nitrate at <60 ppm with no problems. If you have a LFS that doesn't keep any inverts (including corals) on the same system as fish, grab a water sample and test it....I think you'll really be surprised how high it is. I'm sure not suggesting fish be kept with extremely high nitrates, but there is a lot of confusion (IMO) over how high is really dangerous. Nitrates and inverts have totally different rules, of course.

[tymon]

ya all my fish are juv so i keep it low. But what exactly does the nitrate do to the fish like with its health. also are API nitrate test kits good becuase i get to different readings. my seachem says i have 5 nitrates but my API says i have around 10 or 15. which should i trust??

[Mr.Tan]

i've had good results with my API test kit, always seems to be on point and my friend uses it also and he has only good things to say.

My nitrates in my 2 week old tank (almost 3) are right around 10ppm. I've always been under the impression that they should be as low as possible, but this thread seems to be leaning me in a different direction...weird

[MrTuskfish]

Originally Posted by tymon

ya all my fish are juv so i keep it low. But what exactly does the nitrate do to the fish like with its health. also are API nitrate test kits good becuase i get to different readings. my seachem says i have 5 nitrates but my API says i have around 10 or 15. which should i trust??

I think all nitrate tests have a rep of being very inaccurate. I compared my SeaChem with a University lab and it was close enough. IME, API tests go bad within months of being opened.

[MrTuskfish]

Originally Posted by Mr.Tan

i've had good results with my API test kit, always seems to be on point and my friend uses it also and he has only good things to say.

My nitrates in my 2 week old tank (almost 3) are right around 10ppm. I've always been under the impression that they should be as low as possible, but this thread seems to be leaning me in a different direction...weird

There is a big difference IMO & IME) between nitrate in fish only tanks and reef tanks. I would never encourage high nitrates; but, as said above a few times, there just isn't any evidence that nitrate hurts fish. There are several anecdotal accounts involving some species, though. Given the tremendous amount of money spent on nitrate control; I'm sure there would be scientific evidence showing any negative effects on fish. To my knowledge, there aren't any. Again, this is for fish-only tanks. LR made reefkeeping possible and I assume nitrate control is the major reason. I think the nitrate issue just spilled over and it was just assumed, by many folks, that fish suffered with moderate level of nitrate too. Not an endorsement; but prior to Katrina, I kept many difficult fish (Moorish idol, Achilles tang, Regal angel, & others for 10 yrs+ in water that never had nitrate under 80ppm. I wouldn't do this again, just because I want to do my best job with water quality and I'm sure water with high nitrate includes other undesirable compounds.

[snorvich]

Originally Posted by MrTuskfish

I think all nitrate tests have a rep of being very inaccurate. I compared my SeaChem with a University lab and it was close enough. IME, API tests go bad within months of being opened.

Part of the problem is that algae sucks up nitrate and it can no longer be measured. So whatever test you use needs to be modified by what you see. Lots of algae, your testing result is likely to be low.

[Stomkat]

I read a lot on it. There was one SW fish, I can't remember what it was, that couldn't tolerate over 160ppm.

I did raise and breed Betta splendens (FW) for years, and everyone said up to 40ppm was fine for FW. I had one female who's eyes would bulge if nitrates went over 20ppm though.

I think nitrates are a problem because they will promote algae in SW.

It is also a waste product, so I equate it with fish swimming in their toilet. It must be kept in check for their safety.

[greenbean36191]

There is no evidence of negative impacts of nitrate on SW fish.

Nitrate is toxic to FW fish (and humans) because it binds with hemoglobin and prevents oxygen from binding. However, the nitrate molecule competes with the chloride ion for transport across the gills, so in cases where it's impractical to lower nitrate (e.g. fish farms), adding small amounts of salt can prevent the nitrate from being taken up.

The high chloride ion concentration in saltwater prevents significant amounts of nitrate from being absorbed by SW fish.

However, like others have mentioned, generally high nitrate levels are indicative of poor husbandry, which can cause health issues of its own. In well-lit tanks there's also the obvious issue of fueling algae.

[ericauch]

my nitrates were at 50 ppm. no affects onfish and everything else is healty. ammonia is what you got to look out for.

[Drew485]

I guess I know that when breeding Discus ( a fw fish) you have to have the nitrates below 5. So there must be something in nitrates that hurts fish. I know discus are fw fish but all fish were saltwater at some point (Unless you dont believe in evolution) in time so I think the lower the nitrates the happier the fish.

[MrTuskfish]

I bred some Discus and a zillion FW Angels for years to support my SW habit.( My oldest daughter bought her first car with her breeding proceeds in H.S.) I have never even measured FW nitrate.

[MrTuskfish]

Originally Posted by ericauch

my nitrates were at 50 ppm. no affects onfish and everything else is healty. ammonia is what you got to look out for.

True. But a mature, well maintained SW tank should never have ammonia; unless something dies or the system crashes. I don't even test my DTs for ammonia (not recommended) I think just looking at the water and fish would point to any possible ammonia problem.