I lost two fish after a 7 hour power cut and then did some testing my PH levels are fine but i had a small amount of nirite in the water I have been doing water changes for the past four days about 40% of the water andI didn't feed the fish for two of those days incase the problem was dueto over feeding, I got some advice and was told it may be caused by overstocking, over feeding or indiscriminate use of antibiotics, well I have been told I arne't overstocked and haven't used antibiotics so maybe i was overfeeding...anyhow a test four dayls later reveals the nitrite levels have increased further...any advice??

First of all, What are the nitrite levels right now?

I would just keep the water changes up, making sure you vaccum off any old food/poo/scum on the bottom of the tank, especialy in and around ornaments like caves etc.

Then just feed very sparingly for the next few days. Fish can last a long time without food, so dont think you are starving them....

The nitrites should go away within a few more days/water changes

HTH

What size is the tank? What is in it? How big are they? What were the nitrites and what are they now? What is the ammonia and nitrAte?

its a 90 lite aqua one 620 tank the ammonias were at 0 the nitrates were okay and last saturday the nitire was turning the water a very very pale lilac colour when it was tested last night ammonia zero nitrate okay but the nitirite was wrose it turned the water a deep purple colour - it was getting up there in the mid range...... we did have ten neones two of them have died there are four angels and a siamese fighter and 3 zebra danios at the moment.

when we did the waer changes the first three times a lot of gunk came up from the bottom which seems to of cleared off now

More importantly how long has the tank been setup? Normally you shouldn't have any nitrite that you see on your test. Since you are getting a reading, either your filter crashed because of the power cut and is cycling again or something else has died in the tank and you haven't found it.

Did you clean out the filter after the power cut? It's proberly too late to worry about it now.

If you can't find anything dead in the tank treat it like it is cycling again, keep up the large water changes, if you have another tank you could think about moving some of the fish and lowering the load in this tank.

i did a thorough filter clean last night using the first bucket of water I siphoned off the tank on the left side of the filet it was really really balck however on te right side of the filter it was completely clean I am wondering if there is a problem with the filter system? The tank has been up and running for about a month now

I don't think anything else has died in the tank becuase my numbers are okay

Did you clean out the filter with tank water before the power started again??

If not, then when the water flow started again thru the filter, the tank was prolly poisoned.

Recommend water changes to continue, and don't add any more fish for the moment.

Alan 104

yes I used tank water to clean the filter with - should both sides of the filter pads be equally dirty if the filter is working correctly?

after the power cut I did not clean the filter would this be the major caus of my problems perhaps?

after the power cut I did not clean the filter would this be the major caus of my problems perhaps?

Yep, all the bacteria would have died due to lack of oxygen so you get the double hit of losing your main biological filter plus a large amount dead matter breaking down.

What type of filter is it? I used to use fluval filters and found that typically one side would get dirtier first then as that side reduced its flow the other would catch up.

How often do you clean you filter? You don't need to clean them until the flow starts to reduce, having them full of gunk is a good thing its more area for bacteria. Also when you do clean it, most of the time you should only need to clean the sponges, these are there as mechanical filters and stop the larger pieces of gunk getting to the biological media (bioballs, noodles, etc)

I am a little ignorant when it comes to the filter its th built in one that comes with the aqua one set it has the two chambers in it I have only cleaned the sponges once and as i said one was really filthy the other was completely clean. I haven't cleaned the noodles

If you have the filter lid up - is water coming out that side of the spray bar?

We have an AR510, and both sides of the filter get equally dirty...

okay so i may have a problem here

yes water is comming out of the spray bar on the right hand side where the sponge is compleletly clean

salt is often used to help ease nitrite toxicity, 1tbsp per 40L. i have read it a few times on simplydiscus so it should be ok (one of the many wonders of salt), none of your fish are overly senstive but do make sure you keep an eye on them if you do use this as a temporary measure until your bacteria catch back up as individuals can have bad reactions