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Dosing nitrates in a well-stocked tanks

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  • Dosing nitrates in a well-stocked tanks

    Evening, all

    I'm trying to be better about testing my tank and properly dosing fertilizers. After the water change on Monday, the nitrates were 5ppm, so I added 1/8th tsp of nitrate (GLA). Still 5-10ppm on Wednesday, so I added another 1/8th tsp. Today (Friday) it was still around the same, so I added another 1/8th tsp.

    I know that plants like the nitrates to be 10-20ppm, but the fact that the level is constant means that they're taking up the nitrates at about the same rate I'm dosing them. Which isn't too bad! But I'm worried about dosing more, since my tank is pretty well-stocked (55 gallons, 6 baby angels, 8 neons, 7 rainbows, 4 platies, BN pleco, assassins). Awhile ago (months) I accidentally put 1/4tsp in, when I was doing smaller water changes (around 1/3) because I didn't have a water changer and buckets are lame. Anyway it took weeks to get the nitrates below 40ppm. I know that A) plants take up nutrients faster when they're getting the amount they need and B) doing larger water changes now (over 50%) means I don't have to worry about it as much. But I'm a worrywort

    To get to the point: If I dose the nitrates up to the proper amount right after I do a water change, what if the fish put out waste and therefore nitrates faster than the plants take up what I put in? IE if I dose nitrates up to 20ppm, what if it's at 40ppm by the end of the week, even if I don't dose again?

    Sorry if that makes no sense, it's been a long week Thanks for your help, as always!

  • #2
    To avoid stressing the inhabitants you should be dosing enough to attempt to maintain ~10 PPM. There is nothing wrong with 5 PPM either. Don't let the level drop below 5 PPM or there will be an increased chance for cyanobacteria to get started.

    One thing that might ease your mind is to test the nitrate level a couple of hours after dosing your tank. Then you will know the max level going into your tank.

    It does not matter how much KNO3 is being added to a given tank. What matters is that the correct amount is dosed. For example, the recommended KNO3 dose for a 90G tank is 1 tsp; however I dose only 1/4 tsp KNO3, 3 times a week. This is because my tank is overstocked, but with all my plants it works.
    - Dena

    All our dreams can come true if we have the courage to pursue them.
    Walt Disney

    The only true wisdom is in knowing you know nothing.


    • #3
      That makes sense, thank you I'd feel more comfortable keeping the nitrates around 10ppm so I'll aim for that. I always plan to test the tank again after dosing, but I have to leave it for awhile so it becomes evenly mixed, and I always forget to come back