high nitrates

chrisinha said:
my goldfish tank has high nitrates now. how much (percentage) water should i change?
That's hard to say without knowing some things first. For instance, how often do you normally change water in this tank? Just what are the nitrate readins right now?
 
this is a special tank because it's overstock. it's a 10 gallon tank with 4 feeder goldfish in it. i know it shouldnt be this way, i tried to give them away, but so far havent got any reply. i dont want to send them to the LFS because they will be sold as food. i cant afford to buy a bigger tank unfortunately, so i do water changes every other day and test the water everyday.

ammonia : .25
nitrites: .25
nitrates: between 40 and 80
 
Well, if you do water changes every other day then you could get away with as much as 2 back-to-back 50% water changes without hurting the fish.
 
I mean you siphon out 50% of the water, then refill with treated water, or however you do that, then right after that, do another 50% siphoning only to refill it once more. Doing it this way rather than just sucking out 75% of your water reduces stress to the fish.
 
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