i have recently establish a tank and i believe it is cycled because it spiked ammonia and nitrite but now its all reading zero . i believe it been 3 weeks i have over 100+ lbs of rock so i believe it was pretty quick.

so my question is

when do i do the water change? ( im scared i might mess up the cycling IF its not cycled yet. )

i see like on top of the water surface its kinda white.. im not sure if thats a sign for anything..

i have fishes in there already and there healthy.. also im adding a skimmer today.

tank was est. on jan 1 2012... today is the 1-20-12

i have 2 powerhead hitting the top surface. so any advice? that would really be appreciated !

Once a month water changes, at 25%. Or 15% every 2 weeks. You can wait a couple more weeks on a newly established tank. Watch your water parameters. If its cycled, you can do it now. Its really a preferance. Do you run a sump? With anything in it?
Water Changes in the Cycling Aquarium - The First Tank Guide - Don't Water Changes Keep the Biological Filter from Maturing?

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i do not run anything on the sump. but if its cloudy should i be worried? well to me it seemed a lil cloudy

Its cloudy, but its cycled? Go ahead make a water change. You won't hurt anything. Skimmer will help this out some. 100lbs of Live Rock, how big of a tank?

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the tank is 75 gal.. i dont have a skimmer yet but i just purchase one today and tomorrow im putting it in. i know thats a dumb move but i didnt think i needed a skimmer that quick.. but do you think its because i dont have a skimmer? and its cloudy?

also do a 5 gal change? or 10 gal? for a 75 gal

22 gallon water change. Its been a month. I would have thought with all the LR you have in there thatt you would not have a cloudy issue. But is it because you do't have a skimmer, doubtful that the whole reason. Its sounds like a Ammonia Bloom, without seeing pictures. But you say your nmbers are in line. I would perform the 25% water change, youy'll be fine. Do you have a phosphate reading?

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what size are your powerheads? What are your water readings? CAlcium? ALK? Magnesium? Calcium should be between 420-480. Magnesium 1250-1400.

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hey actaully im new to this so i dont have all the test kit, and when i said cloudy i made a mistake .. it was my lights it wasnt good so i changed it out now it looks much better. and with the water change.. im not sure when i should do it since its a new tank..

Once a Month. Doesn't matter if its new or not. Your lights made the tank look cloudy? How so? What kind are they?

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Agreed it is time to do a water change. If you are keeping a tank that is heavily stocked with coral, a weekly change is a good idea. Water changes in a reef tank are about more than just removing impurities. They also bring nutrients with them that the corals need to grow and be healthy. If it is fish only, then the once a month idea is probably fine.

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