high nitrates - always!!! PLEASE HELP

[Bichisaur]

The OP changes water every week then it drops to 50 right? Try doing twice a week till the nitrates drop below 20 then proceed with once a week then check again. Im guessing that the OP missed a WC or two resulting in nitrates creeping up.

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[Aglaia]

i change filters bout once a month

 

[Aglaia]

ok should i change filters twice a month? i will start doing changes twice a week. how much, fifty % each time?

 

[ecoli73]

All you need is rinse out the pads and media with tank water...unless you use carbon, you don't need to change things out...


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[Drstrangelove]

For fun, I worked this backwards, using what the OP said.

100 gallon tank (roughly 85 gallons of water)
50% WC per week
0 nitrates in the tap water
~ 60 PPM nitrates before the WC
nitrates go down then reach 60 PPM in a week
3 fish (largest 6" and 8")

I estimated the fish weight. If one was feeding 10% body weight each day using 75% protein food, this would be correct. Nitrates would be steady at 40-70 PPM. One can vary the % fed or the % protein and get the same result. This isn't saying that is what is being done, but it's numbers that would support the above readings.

It could also be that instead of a 50% WC every week, it's more like a 40% every 10 days, or that the fish are actually larger as well. The above numbers could be ball parking. It's also plausible that the tank contains uneaten food and that the 50% water being removed contains a lot less than 50% of the nitrogen in the tank. Just tossing out some ideas.

OP....how much do you feed and what is it you are feeding? If you aren't feeding a high protein food at the rate of 23 grams per day (or some similar combo), then I'd wonder that you aren't removing 50% of the nitrates when you do the 50% WC.

 

[Aglaia]

i have not weighed the food. mainly its a variety of frozen bloodworms, myosis, plankton, beefheart and flake food as well as one algae tab a day and a cucumber slice a day.
i agree i dont think i am removing the nitrates. how do i remove all of them?

 

[petspoiler]

your food items could be much cleaner & more efficient.
beef heart is not appropriate for fish & pollutes water, eliminate that from your feeding. some discus breeders use it, BUT they also do 100% water changes EVERY day!
greatly reduce the amount of frozen bloodworms, as they are a messy form in water.
flaked foods are not the most nutritious prepared food. they are soft, not as nutrient dense as pellets and easily beak up in water.
I recommend New Life Spectrum small pellets. or Hikari. Fish will get more nutrients out of less food.
feed the smallest pellets that will work for your fish. they should be swallowed whole, not chewed with fish spewing out crumbs while eating.

 

[Aglaia]

pellets, ok. i will do that thank u.

 

[Pomatomus]

there are no nitrate eating bacteria. water changes only answer to nitrate creep

Oh god someone please stop the misinformation in this thread before it gets worse...

It's a bit tangential to this thread, but there are CERTAINLY nitrate-eating bacteria. They grow in aerobic, anoxic areas in aquatic systems. In the presence of nitrate and a carbon source they will produce nitrogen gas and carbonate, reclaiming the alkalinity lost during nitrification. You can make denitrification reactors for any system using PVC parts. My coworker built one for his reef tank. At the sturgeon farm we use 10' tall towers for denitrification.

API kits are certainly less precise than other test kits, but when your tap water tests clean (as noted in post #1) it is obviously accurate enough.

I digress, it sounds like you either aren't removing enough waste when you clean your tank/filter, or you are overfeeding. I agree with drstrangelove that the math just doesn't add up. So I'm going to go ahead and guess overfeeding. It's the #1 problem I see in the aquarium trade. Are you growing baby fish right now? Because if you're not I'd not only look into feeding less, but not feeding daily. I recommend feeding 5 days a week to my maintenance clients. I have worked for 2 marine laboratories and I can assure you than most experienced biologists recommend that you give your fish at least one day off feed per week. The first place I worked at feeds 4 days a week, and the second feeds 6. However that is because it is an aquaculture facility and is trying to maximize the growth of the fish. When the feed is on they are fed every 10-15 minutes!

 

[pops]

I stand corrected, but for the average Joe with a fish tank, those systems are not plausible. yes plants can reduce creep some, but not enough to make water changes unnecessary.