Monopotassium phosphate dosing

[bangtran]

I've been running into an issue were nitrates will run where I want them to 15-20ppm but my phosphates will have a heck of a time getting over .03ppm and phosphorus has gotten to depletion levels. I was given a bag of monopotassium phosphate to dose with but can't find much in the way of an existing calculator for mixing a dosing solution and how much to dose. Any help would be greatly appreicated.

Tank is 61 actual gallons between display and sump.
SPS dominate
7 fish, fed 4 cubes of mysis and enriched brine daily
coral are dosed nightly with roids and aminos

alk 9.1
cal 445
mag 1440
temp 77-78
ph 8.1-8.2

brs 2 part, currently alk is dosing 110ml broken into hourly doses and cal is 125ml broke into hourly doses

 

[Randy Holmes-Farley]

Use this calculator:

James' Planted Tank - Dosing Calculator

Use the entry for potassium phosphate, and if you are using KH2PO4, use 0.64 times the amount dosed (so you are dosing about half as much as calculated).

That said, calculations are not very accurate as a lot of what you dose may rapidly bind to rock and sand, which is fine and expected, but means you may need to dose a lot more than expected.

 

[bangtran]

Thank you.

 

[Randy Holmes-Farley]

You're welcome.

Good luck!

 

[mmakay]

@Randy Holmes-Farley I am in the same position and obtained about 200 grams of Monopotassium Phosphate. According to that calculator, about 6g added to 0.5 lIter of water creates a solution that will raise my 200 gallon (total system volume) by .01 ppm for each ml of solution added. (accounting for the .64 correction) Does that sound right? This must be really potent stuff if I didn’t put a wrong value somewhere.