I was ill - help with high nitrate in tank? - The Planted Tank Forum
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post #1 of 6 (permalink) Old 02-02-2014, 04:52 PM Thread Starter
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I was ill - help with high nitrate in tank?

Post a little long, but want to give enough info so you all can give good advise.

Due to my prolonged illness, my tanks went 2-1/2 months without a water change. Just topping off with RO water.

All tanks are Low Tech, medium to heavily planted, lots of stem plants, and floaters.
I cut my very hard well water 50/50 with RO water that I buy at the grocery - I dose Seachem Flourish, Trace, Potassium once every 10 days or so and Excel at half strength every 4-5 days. While I was sick, all I did was feed the fish and top off water, no fertilizing. Amazing, but plants look pretty good. No fish deaths or illness that I know of in that time. Amazing.

It was a jungle in all three tanks:
2 Fluval Spec V each with a betta and a nerite.
15 gallon that has small fish: CPD, chili rasbora, Otos, Cherry shrimp. It has 2 Aquaclear 20 HOB filters. Eco-Complete.

The two Specs tested pretty good, considering - 0 ammonia and nitrite, about 15 nitrate. But the 15 gal. tested 0 ammonia and nitrite, but 80 nitrate.

I know you are not supposed to deep clean everything at once or it can throw a tank into a cycle. I've only been into this for less than 2 years, though, so could use some advice.

First I recharged the Purigen. I keep one in each tank. Two days ago, I cleaned the Specs - took the bettas out while I did gravel vac, rinsed filter, water down to 1" and refilled. Specs look like they are doing fine. I will go back to weekly 30% changes on them.

But -- the 15 gallon is the one I am not sure what to do about. 80 is pretty high nitrates. Even before I got sick I was having trouble with the nitrates being over 20, sometimes 40, and I think it was from over feeding. I cut down to once a day feeding, and a LOT less food, about a month before I got sick, but I didn't see much difference in nitrate levels. So I've been working on this for a while, but not doing water change for so long certainly did not help.

Anyway, yesterday, the filters were barely working from being so dirty, so I took them apart, cleaned out the gunk from the pumps, rinsed the sponges, pre-filter (to keep from sucking up shrimp), and put in the refreshed purigen in one filter, and put a new carbon pack in the other. Did a light gravel vac - can't do much more in this tank as the plants are to thick. I took the water down to about 3" above the substrate, then refilled. So maybe 65-70% change. I have not put in any fertilizers yet.

I didn't test the water this morning, but I doubt it will be down that much. With cleaning the filters, Purigen, and the light gravel vac with a pretty large water change…. how soon and how often can I do more water changes to get that nitrate level down to a safe level? Large water changes are bad for the shrimp, correct?

I know the carbon packs are not all that advantageous, and am wondering about adding a second Purigen so both filters on the 15 gal. have one. Would that help with high nitrates?

I want to get that nitrate level down --- but I don't want to screw up the cycle, or do so many water changes to fast and actually harm the fish/shrimp.

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post #2 of 6 (permalink) Old 02-02-2014, 05:06 PM
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Nitrate is a sign that you plants are not using up the nitrogen faster than the fish are producing it. This may be caused by not enough plants or another nutrient imbalance.

80ppm really isn't that bad. Old tank syndrome is usually when people don't do a water change for a year or more (unplanted). They will have nitrate levels in excess of 300-400ppm.

Adding a filtration or purigen does not affect the nitrate accumulation.

All you need to do is stagger 3-4 25% water changes this week. Your livestock should be completely fine. Topping off with RO has greatly reduced the amout of other minerals accumulating.
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post #3 of 6 (permalink) Old 02-02-2014, 06:02 PM
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Another way to look at the 80 PPM is how much the current water change is expected to change the levels. Assuming the new water has no nitrate, a 50% should reduce the nitrate from 80 to 40. Another 50 % is expected to reduce it to 20% and you are good! Reading the colors is not precise for most of us so new testing will likely get somewhere in this ballpark for levels. And for practical purposes it is also true that the fish are somewhat used to even bad levels so cutting the nitrate over some time is not really that bad. Good shape, but worth watching for sure.
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post #4 of 6 (permalink) Old 02-02-2014, 06:04 PM
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A filter rinse did the trick for my tanks 80+ nitrate. Also, 50% water changes as needed. I'm sure the dirty filters were the cause though, so retest soon to see! (A rinse won't bring down the current amount in the water, but it will cause less in the future since the debris is gone and not decaying anymore, leading to nitrate)
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post #5 of 6 (permalink) Old 02-02-2014, 08:38 PM Thread Starter
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I just retested and looks like nitrates are between 30 and 40 now.

Thanks everyone for the advice. I hate that I could not keep up with the tanks.

I will do a 25% or so change, then, every other day this week and see how it goes.

I think I will wait a couple days to add any fertilizers. Get in one or two more water changes. A few plants look a little bit pale, but over all, they really look pretty good.
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post #6 of 6 (permalink) Old 02-02-2014, 08:43 PM
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You will know your tanks far better than any of us but there is a chance that the normal daily load of nitrate could be more than a 25 % change can take out so it will still bear watching. Once things do get "off" it sometimes takes a bit to get them controlled again. But it does seem like you're headed in the right direction. Tough when one is knocked down for a long time.
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