High Nitrates

[simon232]

hi all first time posting here sorry its with a problem.

i have a large plec about 6 inch,
a 3 inch kissing gourami ,
a clown loach
a red tailed black botia.

i have had a low ph (lfs said it was about 5.5) problem about 6 weeks ago which i gradually managed to get back to the 7.2 that i have out of the tap.

on advice i upgraded my internal fluval 4 for an external tetra tec ex700. i also added some coral gravel to bring the ph back into line.

everything stablized nicely so i added 10 neon tetras
these survived fine for a few weeks so i added 2 sailfin mollies and a palidine (think thats the right name) cat fish
within 8 hours one of the mollies died. i took him and a water smaple back to lfs and they told me i had a really high nitrates and this had caused the fish to die.
i checked the water myself before i added the fish and it was about 0 nitrates but i am starting to thing the test was not performed properly

i have done 2 50% water changes since my fish died on sat.
1 50% change say afternoon and one sunday afternoon

my reading are now

no3 somewhere between what i think is 80-160
no2 0
ph 7.4
ammo 0.25
kh 0- 40
gh 120 - 180

my tank is a 108 litre

am i doing the right thing with the water changes is there anything else i can do as the nitrates dont seem to be coming down

thanks and sorry for the long post
simon

 

[humpy_the_humphead_wrasse]

u added to much fish at once i think m8. also u upgraded your filter. did you cycle it somewhere else befor or did you put mature media in it? if youve just bought it and stuck it in.... u know your gona have to build the bacteria back in it! 3-4 weeks without fish is recommended. the fact u seem to have ammonia and nitrites in the water makes me think your tank has started cycling again and if so. therell probably be more deaths

 

[Colin_T]

I have to agree with Humpy about the new filter causing water quality issues. If you kept the old Fluval running for a month with the new external filter, then it wouldn't be a problem. However, if you removed the internal and replaced it with a new external filter, then you will have to go through the filter cycling process all over again.
Because you have fish in the tank I would suggest doing a daily 50% water change and gravel clean, and cut the feeding back to once every few days. The less food the lower the ammonia and nitrite readings.
Make sure any new water is free of chlorine and has a similar temperature to the tank.
Nitrate test kits will read nitrite as nitrate. Therefore you should ignore nitrate readings at this stage. Daily water changes will dilute any ammonia, nitrite & nitrate that is in the water and hopefully keep the levels low enough so the fish don't die.
Ammonia is toxic in alkaline water (PH above 7.0). The higher the PH, the more toxic the ammonia is. At a PH of 7.4 even a slight ammonia reading will stress the fish.
Keep doing water changes, reduce feeding, increase aeration/ surface turbulence, and don’t add any new fish until the filter has settled down, (in about a month or so).