Nitrate spike. Why?

Mrs. Burns

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Feb 6, 2006
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Just last week I tested my tank and ammonia and nitrite was 0. But nitrate was between 5 and 10. I tested again today and it was up to between 40 and 60. I did a 25% water change and retested and got nitrate at 40. What should I do? My tank has been set up for 2 1/2 months with fish for 1 1/2 months.
 
How often do you change your water and how much?

Nitrates are a natural part of the tank process -- they are the end product of ammonia and nitrite. They have to be removed/managed by weekly water changes.

Roan
 
My tank is 10 gallon. With 2 male guppies, 1 glassfish and one angelfish. Oh, and 4 ghost shrimp. I was only changing the water every 2 weeks and all was fine. So I need to change water every week to get the nitrate level down? Also, I have read that it is normal to have 40ppm (nitrate). Is this really true? I thought everything should be 0 when the tank was cycled.
 
Mrs. Burns said:
My tank is 10 gallon. With 2 male guppies, 1 glassfish and one angelfish. Oh, and 4 ghost shrimp. I was only changing the water every 2 weeks and all was fine. So I need to change water every week to get the nitrate level down? Also, I have read that it is normal to have 40ppm (nitrate). Is this really true? I thought everything should be 0 when the tank was cycled.
The cycle: ammonia -->nitrites-->nitrates so a cycled tank, unplanted, can and should have nitrates that must be removed via water changes every week.

Unplanted tanks will have nitrate accumulation as there is nothing to process the nitrates. Planted tanks may have 0 nitrates, however that is not always good as plants need nitrates to grow. If nitrates hit 0, then the algae can take over the tank.

IMO an ideal level is ~10-20ppm. Affordable hobby nitrate tests do not accurately measure the nitrate level. I do know that my AP kit will measure at least 10 above what is there and my Hagen kit measures 50ppm when I have 0ppm. At best they should be used for a "ball park" idea of what the level is.

The best way to control nitrates -- which, btw, are not the only things that have to be removed from the tank. There are other things (suchs as Dissolved Organic Compounds) that really must be removed that we cannot test for -- is via weekly water changes. If you do weekly partials of 50%, then you need not worry too much about nitrates unless you over stock the tank.

Roan
 
Basic aquarium principle: Waste product titers/levels in the water are the end result of input.

Nitrate is the most easily measured waste product in unplanted tanks, so we use it as a rough guide to general pollution buildup, as we cannot as easily measure all the rest.

Waste profuct are the end result of additions to the tank and generally match well with feeding levels. If your waste (nitrate as an example) are climbing too fast, it likely means overstocking and subsequent over-feeding, or inappropriate feeding, or just simple over-feeding.

Learning to feed is one of the hardest things about keeping fish. I'm still working on that one. I tend to overfeed myself as well as my fish. ;)
 
Is my tank overstocked? And I only feed once a day. I only have fake plants. What kind of plants should I consider for the size of my tank and the fish I have? I picked up a Lilly Bulb, but I learned they are too big. Also, my test kit is a fw master test kit made by Aquarium Pharmaceuticals. Is that a reliable test kit? I changed 50% of the water and now the nitrate is down to barely over 20ppm. Would it help if I vaccumued the gravel when I do a water change? When I vaccuum, the water isn't that dirty (that I can tell). I know the beneficial bacteria sets up in the gravel too. Does vaccuuming affect that?
 
For an unplanted tank, the gravel should fully vacuumed at each paruial if possible. If full tank full depth is not possible with each change, do at least as much as possible. Substrates are wonderful nitrate/pollution reservoirs.
 
To add what RTR said -- if you have adequate filterage and are not over stocking, you needn't worry about vacuuming up the good guys. Bacteria will house themselves in the place that is best for them to thrive and grow -- your filter.

I've found the AP nitrate kits to err on the side of 7-10ppm+. In other words, if my tanks are at 0ppm nitrate, I will get a reading of 7-10ppm with an AP nitrate kit. Your milleage may vary, however.

Roan
 
It's a good idea to vacuum the gravel when you do a water change. Excess food and debris can sit on the bottom of the aquarium and start to decay. This of course will cause a problem in your tank and effect the levels in your tank. As far as asking if you are overstocked, I would plan on getting a bigger home for your angel fish. They can grow quite large and as they mature they tend to become more aggressive. In such a small tank the aggression level of the angel will be apparent because it becomes a territorial issue. This will spell trouble for the rest of the fish in the tank when the angel decides that the entire tank is his territory. The rest of the fish in your tank will be fine when the angel has a bigger tank.

Be happy!

Marinemom
 
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