Hi all,
will it be an issue if I make separate solutions of potash and phosphate and dose it into the aquarium at the same time.
No, that should be fine. The dilution effect should mean that the PO4--- remains in solution. Iron (Fe) may be more of an issue, dependent upon the pH of the tank water.
the iron impurities in muriate of potash (the reason why the powder is reddish) would react with phosphate at ph > 7 forming an insoluble precipitate
If it is a mined supply it is <"
likely to contain iron (Fe)">.
A quick google shows that RO water is ph7
Google is wrong, theoretically it should be pH7, but it won't be. There are two reasons, pH isn't a very useful measurement in <"
very soft water">, and atmospheric <"
CO2 will diffuse into the water"> , lowering the pH to ~pH6.
which is the best that I should use together with Monopotassium phosphate and potassium nitrate?
You don't actually need to use any of them, can just use those two. They both supply a useful anion (PO4---, NO3-), as well as the K+ cation. If you do want to add more potassium, on its own, using the food grade potassium chloride (KCl) is probably best.
Potassium chloride in the form of muriate of potash. NPK 0-0-60
Last one is a bit of a strange one, the "60" value isn't as a percentage, it is the potassium (K) value expressed as <"
potassium oxide (K2O)">, meaning you need to multiply by 0.83 to get the potassium content.
cheers Darrel