dirty fishtank

Question
Hello- so earlier this year I had battled too high of nitrites and nitrates in my fishtank resulting in some fish being lost. I spoke with someone on here and got it under control. But for the last 3 months i still have been having some issues with it. THe end of October I bought a new fishtank and transferred all the fish into it- a 46g Euro tank.
  I have 2 rather large angelfish, 2 medium and 1 small, along with 2 med to large parrot fish, 1 small parrot fish(which I might be giving away) and then a plecostamus that is getting large, 2 corys and an chinease algae eater. They all seem to be doing just fine, but the tank seems to be getting more algae on the sides more recently and more frequently (I change the filters every 2 months, but rinse them our in between there- its a tetra filtration system that is jsut fine for this tank size). The light is on for 4 hours in the morning and 5-6 in the evening. I thought the pleco would be cleaning more on sides, but he hangs out in the cave thing i have and I hardly see him out.
 Im honestly sick of having to change the water every couple days to keep the nitrites and nitrates under control. I dont want to get rid of any (besides the small parrot since hes the newest) and I cant buy another tank. Just wondering if there is something else I can do to help. I thought of buying two seperate smaller filters- one for each end of the tank. It used to be crystal clear and i wouldnt have to do much of anything for cleaning. can you help? (sorry for writting a long message)

Answer
Hi Kelli,
So it sounds like your aquarium is almost to the point of being well-established. Where the good bacteria colonies -- your "biofilter" is able to take care of the nitrites and nitrates. In a healthy, established system these levels would be as follows- Ammonia- 0 Nitrite- 0 Nitrates - 20 or less.

Make sure to test your tap water as well for nitrites and nitrates. If your tap water has these chemicals already you may have to try using a water conditioner like 'Prime' that helps neutralize both.

High nitrate levels will definitely fuel algae growth. But unfortunately an easy option like adding another filter won't help. Nitrates are best removed most effectively by water changes. However, some hardy live plants like java moss or water sprite can help absorb some of the pollutants as well.

And it simply may be that this specific aquarium and the fish within require a large (50%) water change once a week at least to keep the levels where they should be and the water healthy. Actually, doing one big water change is more effective in the long run than several smaller ones. And some fish are big polluters, requiring up to twice a week 50% water changes to keep the aquarium balanced.
*Always make sure the replacement water is treated with water conditioner and the temp is equal to or just a little bit warmer than your tank's temp.

Make sure to gravel vacuum thoroughly as well.

Water changes are the key to good long-term fish health and clean water. It can be work but the reward is well worth it.

I hope this helps and best of luck!
Susan~