Do you have one of these
most will tell you that 20ppm of NO3
is ok.. IMO
10ppm or less is a good goal.. 40-60ppm can cause problems.. NO3
is a poison, some fish species are able to tollerate more of it before having adverse reactions but some cant handle higer consentrations like the ones your tank is experiancing..
I recomend 25% weekly as a minium for water changes for FW
tanks.. not only are NO3
consentrations getting higher but DOC
's and KH
will build up to poor levels/at times enough to be harmfull to your fish in a months ttime (KH
if your using tapwater to top off with)..
I also recomend if your tapwaters PH
are very close to the peramiters of your tank to do a large (75-98%) water change.. and when I mean very close Im saying that the PH
after the water has been airated for 20 min is within .2 points of PH
and the same KH
reading (normal KH
testkits are not accurate enough to give you a range IMO
If you do not have a KH
testkit or your PH
are not close enough.. start doing 25% water changes daily untill your NO3
level is down to 10 ppm
or less and bump up your normal water changing scedual to 25% a week.. after your first water change If you test 2 hours later and have a 15 ppm
reading increase the water change % untill you can achive less then 15ppm NO3
is the easiest to test indicator that your water needs a greater % and frequency of water changes.. Im not saying its the best indicator or only bad ellement in the water..
the aquaclear 200 pumps 200 gph
(imagine that lol) it will give your tank just bairly 5 cycles per hour.. IMO
that is the minimum for a tank that is not overstocked.. IMO
your tank is at the upper levels of its ability to house fish.. you might want to consider an upgrade.. like to the 300 or just add another 200..
I also recomened unpluging the filter for the one min. a day that there should be food in the water.. (feed only what the fish can eat in 45-60 seconds and unplug the filter durring this time)
clean the fiter media when the debris in the media slows the filters flow down noticably.. this could be 3 weeks or 4 days it depends on the bio-load of the tank..
monthly cleaning of the filter itself (the houseing and such) is just fine :P
78 degrees F is a good temperature for tropical fish.. I recomend that you stop dropping the temperature now..
it seems of the fish you have the tetra's are the indicator fish of poor water quality.. in other words they are the most sensitive to poor water quality that you have had in the tank..
I hope this helps..