High Nitrate Levels - Please Help!!

Hi everyone,

I've had an aquarium for about 4 months now. I had 2 rainbow crabs and 2 feeder fish in it.

Fish are fine but both crabs are now dead.

I have been rigorously testing the water. Nitrites, ammonia, ph, etc... are all fine but I can't get the nitrate levels down which are currently around 80ppm

I do regular water changes (I keep 15litres in the tank and plenty of floating rocks for them), have used nitrate-minus, have used nitrate-reducing filter packs but I can't get the levels down. The water is now brackish (was just freshwater before) and I'm using mineral water for the water changes that is fine for ph and has a nitrate level of 0.

I've got 2 more crabs coming tomorrow. Can anyone please help me as to how I can get the levels down?

Am thinking of getting some aquarium plants so that might help.

Thanks in advance,

Andy

 

what are you water params.

 

do a 20% water cange weekly and see if that helps

 

Don't feed so much.

 

Admittedly I probably fed a little too much before but the crabs have been dead for 2 weeks now.

I've done probably 4 water changes in that time of up to 50% each time. Water is very clear now and these are the current results:

Ammonia 0%
Nitrite 0%
Ph 7.5
Nitrate 80ppm+

I only have 15litres of water (in an 60litre tank) and I am running TWO filters continuously. Oh, and temp is constantly at 26.5 degrees

Thanks,

Andy

 

Your ph is low should be around 8.3 mine is kept at that. Do a water change around 15%. crabs do not like high nitrates.

 

Ok thanks, will do.

To be honest, I seem to have done loads of water changes and they never seem to make ANY difference to the nitrate level.

Should I just change ALL of the water this time but not touch the filters so I can keep some of the good bacteria there? I know the water I am adding is nitrate free. I'm just concerned about the 2 crabs I'm adding to the aquarium tomorrow.

Also, there seem to be conflicting reports on the web about washing out filters. Some say its best to leave them so you retain the good bacteria. Other people say you should clean them with each water change. What do you all do?

Thanks,

Andy

 

How bigs the tank and did u get the crab bodies out? Any fish died in there u didnt fish out?

 

That's a bit of a problem with filter media. You throw out the baby with the bathwater, as it were. You can't really clean the filtration media, you just toss it, and out goes a lot of beneficial bacteria.

For what it's worth, I have no floss, or mechanical filtration anywhere in my 90, except for my protein skimmer, which I hesitate to really consider mechanical filtration. I think your problem is your filters. If you're doing 50% water changes, your nitrates should decrease by 50%. If they're not, something else is producing them faster than you're removing them.

It's probably your filters.

 

Thanks for all the replies.

Tank is 60 litres with only 15 litres of water in it - ie: plenty of rocks for the crabs to use.

The dead crabs came out as soon as I had confirmed they WERENT in a molting phase. Therefore they came out about 18 hours after I suspected they had died.

Should I go for a complete water change (just this once) and maybe lose one of the filters?

Andy