Nitrate Levels

Question
QUESTION: Hi, i was looking for abit of advice how to keep the nitrate levels down in my tank, they always seem to be around 40, tonight one of our dwarf gouramis died after testing the water the ammonia and nitrite was slightly up, both been 0.25 and the nitrate is at 40, we do water changes twice weekly but the nitrate seems to stick at 40, we have tested our tap water and its 0, what can we do to get in down

ANSWER: Hi Michelle,
Sorry to hear that Michelle. Well, first off... How many fish(or inches of fish) and what size aquarium do you have? How old is the system? Water changes are the best way to get the levels of ammonia, nitrite or nitrate down quickly. You can do up to a 50% water change to really dilute the levels, the fish should be fine. Just dont suck from too deeply in the substrate or clean the filtration too thoroughly so you dont harm the biological filter. I wouldnt clean filtration with every water change. About every 15 days should be ok depending on the population and size of your aquarium.
The biggest cause of spikes in any of the big 3 for aquarists is usually excess food or waste breaking down in the system. Having an over crowded aquarium(1 inch of adult sized fish per gallon of volume at the most) or an over fed aquarium are 2 easy ways to get problems going. Another is being lax with maintenance(especially filtration). I would cut back half the amount of food at each feeding for a couple of weeks and stick with 50% water changes every 3 or 4 days and you should see some good results fairly quickly. Sorry for the loss, but dont give up. You'll get a handle on it. Let me know how it goes or if you have any other questions.

---------- FOLLOW-UP ----------

QUESTION: I have just got up this morning to find one of my L134 plecs has died :( so we have the following in our tank:

5 Neon Tetras
4 Rainbow Cichlids
2 Bronze Corydoras
2 Bristle Noses
2 Synodontis Multipunctatus
1 Dwarf Gourami
1 L134 Plec
1 Black Knife Ghost Fish

Our tank is a 100 Litres it has been set up since 2nd May, and our 1st fish was added around a month later, we do water changes twice a week usually on a sunday and wednesday, usually about 30%. we have a Juwel rekord and the filter that comes with it the pads stand on their end so one side is always clogged.
We did a 40% water change lastnight and after testing the water this morning the ammonia is 0.25 , Nitrite 0 , Nitrate 20, so the nitrate has gone down slightly but the water still doesnt seem right its  a little cloudy, we have been treating our fish for white spot aswell would the treatment affect the filter at all? we have taken the carbon part of the filter out as stated in the instructions

Answer
Hi Michelle,
Ah, There are the missing tidbits.
First... Thats an extremely large population for that system. With a population that large you will generally have water quality issues that come and come again.
Second... Most of the treatments available for Ichthyophthirius Multifilis( Whitespot or Ich) contain copper. Copper is extremely toxic in aquaraia, even in the small amounts in a dose of these medications, it disrupts the biological filter, kills our pets(even when used in prescribed dosages, and ESPECIALLY bottom dwellers such as Cats and Plecos), and heaven forbid you accidentally overdose the system. Devastating! And figuring dose is tricky. Because you dont actually have 100 liters of volume in your system, there is much volume displaced by substrate, decor, etc. Carbon deactivates and removes copper from the water, rendering the medication  null, this is why it needs to be removed from the filter before treatment.
I would do a thorough search for any M.I.A.'s, make sure no one is wedged in somewhere or under or behind, adding to the problem with decay.
What are the chances of an upgrade in tank size? You really need to be in the neighborhood of 200 to 300 liters for all of those guys to be comfortable and healthy. That way you can keep the smaller tank for a hospital or quarantine so you dont have to medicate the whole community in the future.  Or maybe to get another 100 liter and divide the community even? If not then the best course is the one youre on. Finish the treatment course for the ich/whitespot(be prepared for casualties, it happens when medicating the whole community). When through the treatment, do a thorough cleaning of substrate and filtration, replace your carbon, and do a 50% water change. Thats the second best advice I can give you(upgrading the size of their home is the first choice). Wish I could be more help and I'm sorry for the losses. Hang in there. Let me know if you have any other questions or if I can help further.