So I'm not sure if these are just meant to go on terrestial plants and maybe aren't pure enough, so I thought I'd ask here for advice before I use them and make some sort of stupid newbie mistake and turn my tank into a toxic waste dump!
So here's what they had (and so what I bought). It's all in powdered form:
LABEL: Potassium Sulphate
ANALYSIS (on the back of the pack): K-41%, S-18%
LABEL: Iron Sulphate - Soluble
ANALYSIS: Fe-20%, S-11.5%
LABEL: Iron Chelate 13% - Soluble
LBEL: Magnesium Sulphate - Epsom Salts - Soluble
ANALYSIS: Mg-9.6%, S-12.4%
What I'm concerned about is that if it's labelled Potassium Sulphate, how come it's only got 41% K and 18% S? Shouldn't the total be 100% if it's pure? Does it have impurities in it?
They also had 'Trace Elements' powder as well, but I didn't buy any of that because the total percentages of the Mg, B etc only came to about 2% so I was concerned what the other 98% of the powder might be, which was an olive/khaki colour. Was I being overly concerned for nothing?
And is the Mg in MgSO4 Epsom Salts really only 9.6% worth of the total? S being 12.4%, so the rest of it must be all O? I guess I'm showing my ignorance of chemistry now with all these questions!
Also, I got both types of Iron because I wasn't sure which was better. The blurb on the back of the Chelate pack says it's "more effective than inorganic Iron Sulphate. Chelate leaves less salt in the soil and is a very effective and safe micronutrient."
Thanks in advance for any knowledge or advice you might be able to share with me!