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Macronutrients

Featured Replies

Looking for a source of potassium sulfate and magnesium sulfate; where do folks obtain these from?

Cheers and Happy Christmas to the list! In 2005 may your plants pearl, your fishes frolic and your tanks look terrific!

Dubbie

I have tried to get these in Wlg, Chemists aren't allow to sell chemicals any more (go figure), the other problem is the small amounts you need, chemical suppliers are only interested in selling Kg's of stuff. I was told to go to the uni lab and ask them nicely. I never did so don't know if it works.

  • Author

As it happens, I work in a lab but I'd prefer to get my own stocks rather than 'borrow' (and our stock of K2SO4 is a bit low at the moment anyway). Sigma chemical suppliers have K2SO4 (250g) for A$26 (or 1kg for A$70). MgSO4.7H20 (a.k.a. epsom salts) is A$40 for 500g. But these lab grade chemicals are likely far purer than we require for our plant fertilisation purposes - I'm guessing folks must have an alternative, and cheaper, source - perhaps from a garden centre?

Warren - can you help?

Yeah i get mine from the local hydroponics shop, nice and cheap, they also sell micronutrients. Come to think of it they have some nice metal hallides there too :D

Some pool shops have both too as they are hardness adjusting chemicals sometimes used in pools...

We're lucky here, there's an industiral chemical supplier. I get 4kg's of either for about $10.

I paid about $70 for all the chemicals I use to make my fertiliser about 5 years ago. I'm about half way though using them now. That works out at about $7 per year for fertiliser instead of $12-15 per week ($624-$780 per year). That's about 100 times cheaper to make your own... I'm dosing a 1200L tank so a lot of fertiliser is needed.

The average tank wouldn't need as much fertiliser as me so the same chemicals would likely last well over 20 years. It's still a lot cheaper to DIY even for a small tank. I got most of my chemicals in 2-4kg bottles. Hydroponic suppliers may be able to sell much small quantities. 500g would likely be enough to last most people a very long time. It should only cost a few dollars for each chemical too. Keep in mind, as the package size gets smaller the packaging cost dominates the selling price. To buy 1/10th of the chemicals I bought will probably still cost about 1/2 as much. But still, it's only the same price a 3 bottles of store bought fertiliser and that doesn't last long...

Hi HummingBird, I can PM you a link to PMDD (poor man's dosing drops) if you like. Has all the ingredients you need and roughly in what quantities to use them. I'd also be interested to see what Warren uses too however... :)

  • 4 months later...
  • Author

Just a followup to this post and a plug...

I managed to get everything from Stockers horticulturalists

http://hydroponics.co.nz/

Potassium nitrate (1kg, $4.49)

Potassium phosphate (250g $1.47)

Potassium sulphate (500g, $2.00)

Magnesium sulphate (500g, $1.77)

Prompt delivery, friendly service, happy to recommend as aN NZ source of PMDD ingredients.

Dubb.

I had Stockers hydroponics make me up the trace element mix as to the PMDD recipe. To make it to the required % of elements thay had to make up around 1.5kgs . This will last me a life time . If any one is interested in buying some (at cost) I could make up some 500 gram packs including mgso4 + kno3 . Not sure on cost yet would need to include post .

Heres the deal with regards to the trace element mix .

100 grams Trace element

150 grams K2so4

70 grams kno3

360 grams mgso4

This is enough to mix 3.3liters of stock solution and @ 1 ml / 10 l .Thats enough to treat 33000 l .

Do check out all the info on the web regarding pmdd before dosing .

This deal is all care no responsibility.

The preferred payment would be a trade . Fert for plants . I will send you the fert you send me some plants . save mucking around sending money .

Send me a Pm if interested .

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