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I'm using Zorfox on custom solution. My bottles are 500ml and each pump doses 2ml. At the tank size of 10 gallons (so a pump per every 10 gallons.) About 1-2x a week on low to medium light. No fancy PAR rated lights, just generic LED floods or shop lights or bulbs.

I was advised to leave the PPM as it automatically is, which is 7.75ppm.

Calculations are as follows: "Add 115.729695699 gm of KNO3 to your 500 ML container. Each dose of 2 ML will raise NO3 7.5 ppm in your 10 gallon tank tank."

BUT I already have nitrates in my water supply. 7.77 PPM. And I also have wood and dead leaves that I add.

So should I not be adding any additional KNO3 at all? Unless I don't do a water change every week? I have algae problems absolutely no matter what I do and no matter how little light I use. Even without any fertilizers.

I typically do a water change every few weeks on most of my tanks, because I really understock and over filtrate. I have a range of sizes, but most are 55 gallons right now, with a few small cichlids, two over rated filters (one HOB, the other a sponge), and pool filter sand substrate in most of them. Not dirty tanks, so not tons of fish waste.

So if I shouldn't add any KNO3 when I do a water change, but should if I don't do a water change, and the KNO3 gets used up and I need more by then, doesn't that mean I'd need like two sets of Macros mixed up for these two separate doses??

I have a big bag of KNO3 and another big bag of KH2PO4. No separate Potassium. (If this is even relevant.)
 

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75g, 33L, 2g and play tanks
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I don't know what your plant stock is like but if your nitrates stay right at 7.7 ppm all the time you should be fine. you could add a little more, mostly I see 10 ppm with 20 ppm being the higher end of what you want to shoot for.

I am no expert but I have also been reasearching. One thing I saw was that algae is from an excess of one kind of mineral or nutrient in the water. So once you find out which one it is that should help. If it's Phosphates for example, PO4, then you're nitrates might stay low cause they are being used more completely than your Phosphates. Again, just an example, but if your nitrates aren't zeroing out then I would assume that this isn't the case. But again, I'm no expert.

All I know is there is a relationship between a lot of those nutrients and I would say that is worth looking into. So getting tests done for all the different things you can should help you out. Your LFS can get you most of that info if you take them some tank water.

or get some Ottos or Siamese Algae Eaters, those are the ones that seem to be the best overall from what I've seen.
 

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7.5ppm dosed 3x weekly is a total of 22.5ppm NO3 weekly. If you change 50% of your water weekly, then you're adding 7.77/2 (3.9) ppm with your water change. You can dose an additional 6.2ppm per dose to reach full EI levels.

If you're going for half EI, then numbers should be in half. Dosing 3.75ppm / dose = 11.25ppm / week, you're adding 3.9ppm from your water change, so you can add 7.35ppm per week from ferts, or 2.45ppm per dose x3 times per week.

To make all of this much easier, invest in some NO3 and PO4 test kits. See what your nutrients are like just before your 50% water change. If either NO3 or PO4 is out of whack, then you know you need to modify your dosing.
 

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Assuming a 10 gallon tank has about 32.17 liters with displacement you would need to dose 249 mg NO3 to get 7.75 ppm. Your recipe would add 284 mg NO3 with a 2 ml dose. Let's check that 115,729 mg KNO3 divided by 250 2 ml doses = 462.91 mg KNO3 per 2 ml dose, 462.91 mg KNO3 x 61.33% NO3 = 284 mg NO3 per 2 ml dose. I think. This Nitrogen topic really confuses me. A dose of 1.75 ml of your solution should actually get you to your target if I'm not mistaken.

If 7.75 ppm NO3 is your goal, it seems to me that you would only have to supplement the amount of depleted NO3 from the remaining water in the tank after your water change to start things back on the target of 7.75 ppm. Otherwise the 7.75 ppm NO3 in the replacement water would get diluted by the depleted half of the water. So if your plants used all their NO3 you would dose 0.875 ml of your dosing solution.

Test kits can be hard to read. You can try diluting the sample with distilled water to make them easier to resolve. If you dilute by 50% multiply the result by 2. This has really helped me lately. It especially helps with tests where I'm overrange on the result.

Definitely get some Potassium Chloride and Potassium Sulphate. Step up the Potassium if your plants get holes in their leaves. Personally, I don't use mixed fertilizer but I can certainly understand the appeal of doing so. You really could have different mixes for different tank maintenance routines. I never thought of that. Pretty clever.
 
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