Water changes when plants reduce nitrate?

[Funkyfishgorl]

Hi,
I’ve had my tank for a month now and I have 8 shrimp and 2 Otocinclus catfish. My nitrates in my tap water are around 30 ppm but I have noticed that the longer I leave my water the lower my nitrates go as the plants are sucking it up. If I leave my water for 1 week the nitrates go down 10 ppm and if I leave my water for two weeks the nitrates go down to zero. Should I leave my tank for longer as all my levels are now 0 which is a rarity with London tap water? Or should I do a light gravel vac of like 5% just to clean up any food or poop on the floor?

I know i should be doing water changes regularly but I’m concerned that adding the fresh tap water with much higher nitrates will disturb the inhabitants.

 

[Retired Viking]

I am an advocate of planted tanks because they really improve water quality. In you case I think you should lessen water changes and maybe increase the number of plants. I read several articles on how moss balls reduce nitrates. Some articles even rate them #1 or 2 at removing nitrates. You may want to throw one or two in your tank. How big is your tank?

 

[Funkyfishgorl]

I am an advocate of planted tanks because they really improve water quality. In you case I think you should lessen water changes and maybe increase the number of plants. I read several articles on how moss balls reduce nitrates. Some articles even rate them #1 or 2 at removing nitrates. You may want to throw one or two in your tank. How big is your

I am an advocate of planted tanks because they really improve water quality. In you case I think you should lessen water changes and maybe increase the number of plants. I read several articles on how moss balls reduce nitrates. Some articles even rate them #1 or 2 at removing nitrates. You may want to throw one or two in your tank. How big is your tank?

Here is a picture of my tank for reference. It is an 100 litre tank (aprox 22 gallons) so is quite under stocked atm as I’m waiting for my shrimp to start to reproduce before I add any fish that might eat their babies. I already have 3 moss balls and some floating plants that are supposed to help witht the nitrates. I can tell the plants are doing their job I’m just not sure when to do a water change as I never see my levels rise, I only see them decrease in the case of nitrates and ammonia and nitrite are always at 0ppm.

p.s yes I will be trimming the water sprite today, they’ve grown like crazy

 

[Essjay]

There are all sorts of other things in the tank that plants do not remove. Fish excrete more waste products than just ammonia (I once worked in a hospital lab and we tested urine for many things; fish excrete similar, if not the same, waste products); they secrete hormones which end up in the water, etc. All these things also need to be removed by water changes. Unless a tank is very lightly stocked, we should chnage at least 50% a week.

 

[Byron]

I concur with others on maintaining significant water changes, this really is crucial to a healthy biological system. But that does not address the nitrate issue, and that is important too.

I am frankly surprised that nitrates at 20 ppm are being removed at such speed. Usually plants do not take up much in the way of nitrate, they prefer ammonia/ammonium and only turn to nitrate when the ammonium is insufficient (in balance with light and other nutrients). I'm wondering if there is something else here.

If you are using the API nitrate test, you need to shake Regent #2 for a good 2 minutes (not the 30 seconds in the instructions) before you add the drops, or it can cause a faulty (and higher) reading.

Are you sure the tap water is 20 ppm? Let a glass of water sit 24 hours, then test nitrate. This normally is not necessary for nitrate, but it is worth doing.

Are you adding any substances to the tank water, other than conditioner? If yes, please list, and the brand of conditioner too.

In the end, there are ways to deal with nitrate in the source water, and some members here have experience and can advise. But first let's sort out the above, just in case.

 

[Retired Viking]

There are all sorts of other things in the tank that plants do not remove. Fish excrete more waste products than just ammonia (I once worked in a hospital lab and we tested urine for many things; fish excrete similar, if not the same, waste products); they secrete hormones which end up in the water, etc. All these things also need to be removed by water changes. Unless a tank is very lightly stocked, we should chnage at least 50% a week.

In his case I would say lightly stocked (8 shrimp and 2 catfish.)