I bought this product last week before I learned about dry ferts, Im sure itll do the same job, but Im unsure as to equivalent tsp > ml doses.

If, when using EI, the suggestion is 1/16th tsp of KH2PO4, what amount in ml of the Seachem equivalent would be equal to it?

Thanks for the help.


Guaranteed Analysis as printed on the bottle:

Available Phosphate : 0.3%
Soluble Potassium : 0.2%

From Chuck Gadd's great website: KH2PO4 is 69.8% phosphate, and it weighs 4.8 grams per tsp. 1/16 tsp of KH2PO4=0.3 grams, which is .209 grams of phosphate. That would be the dosage of phosphate you need. .209 grams of a liquid that is .3% phosphate means you need .209 divided by .003, or 70 grams of Seachem Phosphate per dose. 70 grams equals 70 ml, so that is the equivalent dosage. That stuff isn't going to last very long being dosed at that rate!

LOL your telling me! I just reread the bottle and found this formula:


0.8 x Vol x A = dose (ml)

where A = the desired increase in ppm. Which perfectly fits your explination. At first, I misread the formula and put the decimal place in the wrong place and was wondering why the hell I couldnt get a reading after adding 6ml of the stuff.. now I see why!!! it was about 1/10th of what was needed. PMDD here we come.

No wonder I cant shift my BGA problem, Ill use up this bottle then go dry, Ive ordered dry KNO3 as thats reading 0ppm as well. With no PO4 and no KNO3 no wonder Im getting BGA. Until I get the KNO3 (few days), Ive turned off 1/3rd of the lighting to slow things down abit. Ill be so happy to see the back of it and start growing the tank properly.

Thanks for your help Vaughn

Mmmm... when we put these numbers in APC Fertilator, the results seems to be very different.
This could be a bug from Fertilator?

Ive not used that one, but the figures stack up perfectly on Chuck's Planted Aquarium Calc.

Just redosed using the proper formula and PO4 is now sitting a nice 2ppm, amazing what you can do when you read things properly with the help of someone with a brain *points at you Vaughn* Thanks buckets. Note to self, dont use liquid ferts unless you have a spare shed to store them in and a lottery win to buy them with.

I'm not going to debate the calculators because well......I do not need nor use them personally.

What I will suggest is a simpler ansd cheaper solution, go to Aqua Essentials in the UK's site.

Order KH2PO4.
500 grams will last you 10.68 years at 1/16th 3x a week.

Regards,
Tom Barr

hehe, done and done. As well as the other ferts I need.

Im going to go full EI once my new shiny pressurised CO2 system arrives on Thursday. Hoping that will shift my GBA without having to go blackout.