MSU & Supplementing Magnesium

[Masdyman]

Originally Posted by Ray

First of all, a TDS meter is just an inexpensive electrical conductivity meter with a built-in conversion factor to ppm solids. Unfortunately as solutions differ in their ionic content, that "conversion factor" needs to be different for every solution. Read TDS and EC.

Epsom salts, as we can get it, is actually MgSO4-7 H2O (that is, only 48.8% MgSO4 by mass) , and has a density of 1.68g/cc. (The bulk density of the powder is probably lower than that, but as I don't know what that really is, we'll assume the 1.68 number.) Therefore, 1.25 ml x 1.68g/ml x 48.8% = 1.025g of MgSO4 was added to 1kg of water, meaning the solution is actually 1025 mg/1.001025kg = 1025 ppm MgSO4

Yeah ,i have come to accept that TDS meters are of no use only to give a idea if a target mixture is near correct at time of feeding/mixing .

If at approx 1025ppm at 1.25ml per l that is 5.68ml to 4.54 l or 1 Gal ,one of the posters said someone using 2TBLS that would be 30 ml GAL so would be about 6000ppm so the Mg can have no effect on burning roots then right ?

[Ray]

Originally Posted by Masdyman

If at approx 1025ppm at 1.25ml per l that is 5.68ml to 4.54 l or 1 Gal ,one of the posters said someone using 2TBLS that would be 30 ml GAL so would be about 6000ppm so the Mg can have no effect on burning roots then right ?

No, that's wrong.

If you'll go back a reread the thread, the comment was that the Epsom Salts was fed with plain water at different times from fertilizer, as otherwise there was a toxicity. I'd attribute that to simply too high of a concentration of stuff in solution.

[Masdyman]

Originally Posted by Ray

No, that's wrong.

If you'll go back a reread the thread, the comment was that the Epsom Salts was fed with plain water at different times from fertilizer, as otherwise there was a toxicity. I'd attribute that to simply too high of a concentration of stuff in solution.

That is how i read it as well ,but surely if at my levels i was reffering to at 1025 ppm that at the higher dose of 6 teaspoons/2 tbls then around 3000 ppm without any feed added . So the high tds with Mg cannot have the same effect as high feed tds ?,was my point .