what are toxic levels?

[scuba_jez]

hey everyone. I've been looking around a fair few places and have established through trial and error that ammonia > than 1.2 ppm will kill fish a probably only > .5 is safe.

what ammonia, nitrate and nitrite levels are 'safe' for fish when cycling a tank and what nitrite levels are safe after cycling a tank ie when a water change is needed.

thank you all for your patience but i looked at the FAQ and this information wasnt there. the information on my test kit for ammonia is ******* misleading!! it killed the poor danios. lets sue em!

 

[modernhamlet]

No level of ammonia or nitrite is "safe" for fish. None. Even a relatively small amount of either of these is poisonous and detrimental to their long term health. This is why we encourage fishless cycling. Faster cycle, no fish harmed.

If you are cycling with fish (which seems to be the case), do water changes as much as necessary to keep the ammonia and nitrites below .5ppm, preferrably lower.

Nitrates are a little more tolerable, but still poisonous. A water change at 40ppm is probably advisable, but most fish can tolerate higher levels. 80ppm is starting to get pretty high. I keep my tank below 20ppm at all times.

What size is your tank?
What and how many fish are you cycling with?

 

[freddyk]

Ammonia becomes more toxic as the ph gets higher. .5 ppm may be tolerated by fish at a ph of 6, for instance, but may quickly kill at a ph of 8. These numbers don't mean anything, they're just being used as an example.

That said, as modernhamlet said, there is no such thing as a safe or tolerable level - it's more a question of what levels will kill them quicker - 0 is the only acceptable number for ammonia and nitrites.

 

[scuba_jez]

hey again

firstly i would like to appologise for my wording - i should know better than to use the word safe and ammonia in the same sentence. anyhoo

i tried cycling with fish - they died (big learning curve started)

and then left my tank with a fairly large ammount of ammonia (1.2 ppm) i should have realised this was too high but the idiots at the pet store said i'd be fine with just a pH test so i only found out the ammonia levels after they died.

my tank is only a baby 28 L (7 gal?) and the ammonia has gone up to 2.4 ppm after using a product called cycle. i will buy a nitrite test kit tomorrow (although im sure nitrite will be way high) and my nitrate level is 5 ppm which im really happy about since that means i have *some* beneficial bacteria living and the two poor fish didnt die in vain.

btw i just put a snippet of old filter media under some gravel. since i have an UGF it should speed up the process a bit.

I'm looking to put a couple of fish in the tank after the ammonia levels drop to a safe level, does this sound viable or since im this far without fish should i just go the whole nine yards and go for the fishless cycle?

thankyou very much fredyk and modernhamlet i will write out your stats and keep them with my test kits

 

[rdd1952]

Ammonia becomes more toxic as the ph gets higher. .5 ppm may be tolerated by fish at a ph of 6, for instance, but may quickly kill at a ph of 8. These numbers don't mean anything, they're just being used as an example.

That said, as modernhamlet said, there is no such thing as a safe or tolerable level - it's more a question of what levels will kill them quicker - 0 is the only acceptable number for ammonia and nitrites.

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As stated, pH greatly affects ammonia toxicity. At pH levels below 6.0, ammonia changes to ammonium which is non toxic. I believe that temperature also has a similar effect when temps drop into the mid to low 60's but for tropicals, that is another problem in itself.

The levels that will kill fish (or seriously shorten their lives) will vary depending on the hardiness of the fish. As already stated though, the only acceptable level is 0 for nitrite and ammonia.

 

[freddyk]

does this sound viable or since im this far without fish should i just go the whole nine yards and go for the fishless cycle?

Absolutely do a fishless. Even when ammonia doesn't kill a fish it is always damaging them whether you see it or not - and damage caused from ammonia is irrepairable and will affect long term health. When you have your cycled tank you'll be able to add fish and not worry about poisoning them - worth staring at an empty tank a while longer. Are you continually adding ammonia.

PS. cycle is a waste of money. If you were able to get enough established media for the filter on the other hand, you would end up with an instantly cycled tank.