[rayhwong]

Hi,
I ran a search on potassium dosing and I still have a few questions.
How exactly do you know how much potassium to add? I have a high bioload and dont need to dose KNO3.
Should I just use Tom Barrs estimative index?
Ive suggestions from 10-20ppm K. How high can it go before you see calcium uptake problems?
Thanks.
- Ray

 

[TeeItUp]

There will be more knowledgeable than I that will reply but you will be safe dosing twice the amount of Potassium then you are dosing NO3.

 

[RoseHawke]

Er, I'm sort of in the same boat. I've been testing daily (so far) and so far have been adding 9ml solution of KNO3 daily to my tank. Estimating 40 gallons and the solution mixed from 2T in 250 ml water (each ml supposed to add 0.55ppm nitrate per 40 gal.) Testing showing 5ppm and dosing to get to 10 ppm (testing phosphates at the same time and dosing to keep up around 1.0 ppm of phosphates.) So am I to assume that the tank is using up Potassium at the same rate it's using up Nitrates and dose accordingly? IOW with an initial dosing that (presumably) got it to the recommended 20ppm, I should assume it's using 10 ppm K per day and dose to 10ppm K daily? From being as clear as mud all this is becoming as something seen through a bit of frosted glass...there's light there somewhere!

 

[bharada]

I, too, have recently adjusted my dosing routine to include 2X-ppm of K that I dose in NO3. I guess with my fish load I was having a lot of NO3 and PO4, but not enough K as plants like Ludwigia repens and ovalis would develop pinholes at an alarming rate.

 

[rayhwong]

Are there any other symptoms of K deficiency besides pinholes? I heard of yellowing of new growth as one?

 

[bharada]

Chuck Gadd's deficiency page lists pinholes, yellowing areas, and whithering leaf edges and tips.

 

[PeteyPob]

I have a quick question, how doI test for potassium in your tank? My fish load keeps my nitrates at a constant 5ppm and phosphate between .2-.5. I have greg watson powder potassium but havent found a site to help my measure out my correct dosage.i am currently using Leave Zone by aquarium pharm. until I can figure out how much to add. Anyone point me in the right direction? THANKS!

Pete

 

[Rex Grigg]

There really is no test for potassium. So you just dose to the level you want (up to 20 ppm) and then dose each water change. If you want to know how much to dose then head over to http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm and download the calculator.