75 gal water change then ammonia

[ashobson]

I have a 75 gal fish only tank it has been up since fathers day it started with the contents of a 54 gal corner tank more live rock was added along with more sand it had a mini cycle and has never showed sighns of ammonia or nitrites since. I started doing water changes it was set up with tap water and has had some allege growth and red stuff growing on the sand so I was also doing water changes on my 29 gal reef tank so I decided to mix up and change the same amount in the 75 gal I changed about 30 gals in the last week and a half. the water has a brown tint could this be the ditmiats or the allege dieing off from the nitrates coming down from 150 to 2.5 to quickly? I think this is what is happing I changed out another 10 gals tonight hoping to help the ammonia back to 0 it is curtinly between 0.50 and 0.25 about the same as the min spike it had during the min cycle. I have bought a ro di unit but it has not came yet. so I will run by wallmart tomorrow and get some more. i need to do another weekly change in the 29. Poor fish have to go without supper tonight

 

[ashobson]

Ok nobody have any ideas why all of a suden after never changing water and then starting to that I would have this spike?

 

[MantisFreak]

Did you mix it with a powerhead for at least 12 hours (24 hours is better) before doing the water change? Freshly mixed saltwater often contains ammonia that has to be off-gassed. Even if it doesn't contain Ammonia, newly mixed saltwater is quite caustic.

 

[malkore]

massive algae die off from the loss in nitrates you say? all that algae has to decompose, and it may be creating more ammonia than your bio filter can handle.

Small water changes for reef tanks...10% or so.

 

[Phyl]

Did you wash out any filter media in the process? If you did then I'm guess you've also cleaned off some of the good bacteria that was processing your system. The water change alone shouldn't be enough to cause a cycle. Unless you have massive algae I don't think that the die off is what you're seeing.

You can get rid of a yellowish tint to you water by running carbon (not sure if that's what you're seeing or not). Diatoms don't usually sit suspended in the water column, that's more of a sit on the rock surface/sand type of algae (and of course all over your glass).

.5 is a pretty good ammo spike. Keep on top of the water changes over the next week to try to get them back to zero.

 

[ashobson]

Have not tested it this after noon yet this morning it was back down .25 this morning yes I mix the water over nite. with power head in plastic tote.the Water is clear again Today I was thinking that the allege die off could be the colpuert. i am sure it was the problem I never did water changes before the tank always tested fine but I though maybe I could get reid of the allege with the ro water.