nitrate stays at 10 ppm

John B. said:

Sorry the phosphates are between .50-.75. What if I try raising the phosphates to about 1.00 or 1.25, do you think that may help? I am using an AP test kit.The phosphates are being used up because I have been dosing about .25 every 2-3 days. Any ideas?Thanks,
John

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I don't think increasing PO4 from 0.50 - 0.75 ppm to 1.00 - 1.25 ppm will make any difference. As long as there is some PO4 we are ok.

I would make two solutions:

SS Standard Solution
KNO3 - 20 g
KH2PO4 - 6 g
K2SO4 - 16 g
in 500ml

PF PO4-Free solution
KNO3 - 20 g
K2SO4 - 20 g
in 500ml

You can dose daily 8ml of SS and 8ml of PF solutions. This will give you the right NO3 : PO4 : K ratio. No more worry about the unknown K. Test NO3 and PO4 in one week. If there is still any problem then we need to look at the Ca and Mg issue.

Edward

John,

Have you tested the test kits?
See if they are accurate or not. Often with NO3, they are not.
I use a Hanna colorimeter for several parameters.
I calibrate these with known standard solutions.
Lamotte kits tend to be the most accurate hobby kits for NO3.
You can make a simple standard solution easily by using the fertilator on this site.
Make a series of 2ppm , 5ppm and 10ppm and 15 or so, whatever range you think the NO3 might be at.

If you are not adding KNO3 to this tank and the NO3 is not going down, the CO2 is at 30ppm, the light is 4w/gal and your PO4 is declining, something is up.

If plant health is decent, and the fish load is moderate, tap is clean as far as NO3, the kit is the most likely problem.

Careful not to trust a test kit too much, many hobbyist do and that has caused many issues over the years with NO3 and PO4 in particular.

In any event:
I'd add 1/2 teaspoon KNO3 at least 2-3x a week to the tank no matter what the heck this test kit says. Do the 50% weekly water change. You can dose higher or lower, but at higher lighting levels, more nutrients and CO2 are required to maintain a good balance.

Adding more than what is needed does not cause algae.

I'd add 10mls of traces 3x a week as well.

That will cover all your bases and answer you questions while improving the plant health and robustness of the tank.

Regards,
Tom Barr

aviel said:

Hey tom,

Why dose traces 3 times a week? Why not 7 times a week? Why not 14 times a week?

John,

Could you please let me know your dosing scheme in the last weeks. I am talking in particular - trace dosing. Which product and how much?

Aviel.

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Less than 3x/week at higher light(3+w/gal depending) depletes the levels and reduces uptake, even if there is some still left and measurable.

You can dose 7x or daily or 2x a daily, that's up to you. I personally like to leave and ski and Mt bike on the weekends

I generally suggest for folks wanting to drive the tank at higher max rates/lighting with the every other day routine.

Main thing is to do your routine consistently, this becomes more and more critical at higher lighting.

I use dosing pumps on client tanks with high light without autodosing timers.

I'll add macros the day of the water change
I'll add traces the following day, I'll add each of these every other day from then on.

So per week: 4x of macros
3x a week of traces

I've used a number of traces over the years, Sera, TMG, Flourish, dry mix Plantex, Kent etc.

I like Flourish and TMG
Plantex is cheap.

I add about 5mls per 25 gal worth of tank per dose.
1/4 teaspoon of KNO3
1/16~ or so of PO4

you can scale this up/down however you wish.
That prevents most any plant from deficencies except for GH/CO2.

You can use the fertilator here to dose to whatever ppm range you wish to try out.

Regards,
Tom Barr