There seems to be some math issues with the calculations...

What do you mean?
Thanks.

the numbers dont seem to agree with the factory

Here is a link that might be useful: flora calculator

Ah. Thanks.
With the exception of Sulfur and Iron, I'm only off 10% or less. That's pretty impressive considering I only used the percentage values on the back label and didn't actually try to break down their various ingredients when making the calculation. Interestingly, all their concentrations used one or more sulfate, yet only one label listed sulfur in the concentrations.
Anyway, it was really an exercise in web design. Just thought I'd try and make it somewhat practical and or useful.
Thanks for the link so I have something to compare it against.

Grizzman, your math might be off, but I don't believe GH's math on the label is accurate either. I could easily be mistaken, though. I just mixed 10 gallons (approximately 38L) of nutes in EC 0 rain water yesterday. I let it sit over night. I have found that following the instructions on the label for GH always leads to a much higher EC (ppmx500) than what their website claims. I used 5ml gro, 10ml micro, and 15ml bloom per gallon. The solution measured EC of 2.4 on my meter and that is normally what I get. According to the GH calculator that is a total difference of about 400 ppm. I always follow the instructions initially and later adjust to where I want it before giving to the plants. Have you checked the EC to compare your math versus actual EC readings starting with water with an EC of 0?

With the same token, I'm not ruling out a meter malfunction on my end. But, I've been using the same meter for quite awhile and this has been the norm the whole time. The plants don't seem stressed and results are repeatable.

This thread got me thinking about the meter malfunction possibility and that it probably wouldn't hurt to find out for sure. So I took it to the hydro shop and compared readings with theirs. I had to get some stuff anyway. It's accurate, so the readings I stated above are correct.

The most common error when comparing total (actually measured) PPM with the supposed content in a mix is that:

Calcium, Sulfur, Magnesium (we do not consider 3-5 PPM of trace elements and a actual purity of all components of only 97-99%, do we?) respectively one of them is left out in the calculus.

Further more, one needs to consider and transform the data of given P2O5 and K2O to actual PPM-content of P & K, as they (P2O5 and K2O data) do not correspond to actual PPM in a solution.

Anyway, if you want to compare actually measured EC (PPM-content) in any solution with specific data, - you need to consider A. that your EC-meter measures ALL RESOLVED SALTS that are included in a solution (whatever they may be and if mentioned in the product's specs or not), including those of the tap water you use for your solution. B. you need to know the precise, proper and unmistaken content in PPM of given data (product) to be compared with. Otherwise your calculus can never be accurate.

Despite the fact, that I tried to explain the tricky discrepancy between industrial convention and atual PPM already several times and in different ways, apparently it wasn't understood or taken in consideration. Sorry, there is no way around it.

See link ->

Here is a link that might be useful: Actually same problem as described here.