Tanks Gone Weird

moochy13 · May 22, 2011

yesterday, i decided to give my tank a proper breakdown and clean, hoovering places i didnt hoover before, splitting plants to give to friends as i had loads, removing a couple of fish, and changing where my plants were. long story short, i got all my fish and wood/plants into a dog bath and 2 buckets with tank water, covered them and got on with cleaning tank. external filter was turned off but left full. i probably removed 100% of the water that was in the tank originally, as i had to put more water in just to give me enough to finish the hoovering. normally, my filter/maintenance regime can cope fine with my tank, which is a bit overstocked, but everythings healthy and growing, no unexplained deaths in months. i also removed a lot of the plant matter, taking out the largest/deadest leaves, and splitting one of the plants in half for a friend.

however, this morning i got up and checked the fish to find them gasping at the top, so i tested my water and everything was reading in dangerous amounts :crazy:

quickly removed a decent amount of water, and replaced with it with fresh, dechlorinated water. i also went and got 20L of water from my other tank. this had a water change yesterday aswell, so its pretty clean, but i didnt know if maybe i had removed all the food for the filter in taking 100% of the water out, so i wanted some 'dirty' water back in. whether this is right or not i dont know, too late now. i just changed out another 20ish litres for fresh water.

im noticing visual improvment in the fish, however i suspect i will be changing water every day for the next week at least. i was always led to believe from this forum that a 100% water change could theoretically be done. i took all precautions, nothing 'contaminated my tank', chlorinated water didnt come into contact with my filter, or fish obviously. filter is pumping as normal, fish were kept in the dark for as little time as possible (about 45 minutes i reckon). the fish arent the problem anyway, the water is. its as though my tank has been running with no filter for the last month, yet yesterday all water was fresh from the tap, with dechlor.

what could have happened ? im not overly concerned, im at home enough to keep an eye on them reguarly and water changes will hopefully see me through, but im just confused as to how i removed loads of dirty old tank water, replaced it with nice clean fresh water, and ended up with the worst set of test results ive ever had :unsure:

Westwood · May 22, 2011

How long was the filter left standing?
Even though the media was wet it can still starve as there is no circulation.

moochy13 · May 22, 2011

no more than an hour and a half, if that.

BigbruiserAl · May 22, 2011

ill go for a ph swing, often the ph of water thats settled is often diffrent then out of the tap with a 100% i would prob guess shock and diff temp of water even if only 1-2c

moochy13 · May 22, 2011

but why would ph swing and temp difference increase my ammonia, nitrate and nitrite levels massively ? the fish temselves arent diseased or ill, the water itself is just out of whack.

StandbySetting · May 22, 2011

Temperature swings wont have a significant effect on filtration unless it's drastic, a few degrees will make no difference, also carbonic PH swings don't tend to affect filter bacteria, the tap water and tank water should be of similar general hardness so I can't see that being and issue either. The chances are you disturbed a lot of decaying detritus when you up rooted the plants, which would make sense considering you have high levels of ammonia/nitrite.

moochy13 · May 22, 2011

the plants came out before the water came out though - the majority of what got kicked up when dismantling the tank was what i was hoovering out. granted, i couldnt get the sand spotless, but it looks no worse than it ever has done. i had nothing but sand in the tank, and hoovered till water was about an inch deep, before putting some more water in and hoovering that out down to about 3 inches.

StandbySetting · May 22, 2011

Ammonia dissolves into the water as material decays, so you could have disturbed a lot of ammonia, removing detritus doesn't necessarily mean that you've removed all of the ammonia, the water change you did will have diluted it.