Cycling question

Panicked Reefer

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So I am cycling my tank. My nitrates have shot up to 80ppm. I am still showing .50ppm ammonia and .25 Nitrite. When should and how much should my water change be? Tank is a 75gal and has no live stock at this time.
 

Azedenkae

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So I am cycling my tank. My nitrates have shot up to 80ppm. I am still showing .50ppm ammonia and .25 Nitrite. When should and how much should my water change be? Tank is a 75gal and has no live stock at this time.
The water change should come at the end of the cycle and only if nitrate is too high. :D That's what I'd do.
 

Azedenkae

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How much of a water change would you do on a 75DT with about 20 in the sump?
So 95 gal. I'd take the concentration of nitrate from 80ppm down to 20ppm, so theoretically, a 75% water change. I.e. close to 75 gallons. Which is... a lot.

However, bear in mind that nitrite affects (most) nitrate tests, because (most) nitrate tests actually convert a portion to nitrite first, then measure that, so even a small amount of nitrite can skew nitrate readings. It can be as much as 1ppm nitrite reading as 100pm nitrate, so your 0.25ppm nitrite might cause nitrates to reading 25ppm higher, for example.

By the way, have you considered what you'd do to keep nitrates in check long term?
 
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Panicked Reefer

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Ok, so it is best to not worry about nitrates until the nitrites zero out. My concern is this, I used Dr Tim's. It stated on the card to dose 4 drop per gallon of the ammonia. If using live sand start with 2 drops per. I did this. It resulted in a 2ppm reading the next few days. When it came time to dose the 2nd time I dosed 4 drops. My ammonia shot off the api test. It has since subsidied to .50 ppm for several days. My nitrite raised and fell down to .25 for several days. I checked Saturday and my nitrates were at 10. Sunday was 20. This morning they were at 80. I'm concerned that if I don't remove the remaining ammonia via a water change I will only exacerbate my nitrates. Im not sure if that's sound logic or not. This is my first tank. I have a refugium (not running throughout the cycle) and hoped between that, water changes, sensible stocking and feeding I will be able to keep it under control.
 

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