Ammonia spike after large water change

[mjvincent]

I have been having problems with elevated nitrate levels (20 ppm) and wanted to reduce them... I had done a number of 10 percent water changes on the 32 gallon hex with little effect (not significantly noticable on the color chart). On Saturday morning I thought I had lost my new Flasher wrasse that I had put in the previous day, so I said what the heck and started a big water change. I drained 9 gallons out of the 32 gallon hex and moved some rockwork around (not sure how much water my 28 pounds of rock and 40 pounds of substrate displaces) which probably equates to a 40-45% water change.

After the change I tested the water again and by golly the nitrates did drop in half and oops! the ammonia jumped to .50! I ran to the store and got some prime and double dosed the tank and everything is fine. Checked the ammonia levels last night and they are back to normal.

Anyone know why ammonia jumped so quickly and dropped so quickly again?

[fishfreek]

Did the fish really die? If so did you find its body? If not then that could be the cause of the ammonia spike. When you remove the water from the tank during a water change how do you do it? Do you syhphon the detris off the rock and substrate or do you just syphon out the water? Do you by chance have any more of the makeup water to test it for ammonia?

[electrikat]

You didn't test right after the water change did you. I've found that I usually have to wait at least 12 hours befor testing after a water change. It takes that long for the ph to settle in and for the two kinds of water to merge and match temps and stuff. If I test right after, and I have before, I get the screwiest results I've ever seen.

[mjvincent]

Originally Posted by fishfreek

Did the fish really die? If so did you find its body? If not then that could be the cause of the ammonia spike. When you remove the water from the tank during a water change how do you do it? Do you syhphon the detris off the rock and substrate or do you just syphon out the water? Do you by chance have any more of the makeup water to test it for ammonia?

No nothing had died... I think it was just the volume, the movement of rocks and everything combined that caused a momentary spike in ammonia. Everything is fine here, just wanted people to know what could happen...

[morphviper]

The problem with water changes is that it pulls out a ton of bacteria and isn't replaced. When you stirred up the tank it released some gunk or decayed food that has been left idle. The change of water didn't allow enough bacteria in the tank to consume what you stirred up. your nitrates can be consumed by growing algea or a protein skimmer. I have used a nitrate sponge once that did good.