How long did the batch last? The values quoted in the IFC was the figures we was advised should be enough, doubling the dose makes sense if it works and its a relative very small increase once its is dosed. The added cost is also irrelevant and worth it if it prevents the mold.
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Mold in DIY fertilizers with potassium sorbate
- Thread starter MrClockOff
- Start date
MrClockOff
Member
The batch supposed to last about 26 days but for simplicity I prepare new one every 21 days (3 weeks) and discard remaining. This has few benefits. I can set reminder to repeat every 3 weeks and if I miss it I still have up to 5 days to refill. I never run out of fertiliser so don’t have to bleed the delivery line.
Jumping in here a bit late, but based on my experiments and others here on UKAPs,
- Missing out potassium sorbate and/or ascorbic acid as they are "E" numbers so must be bad. ( E202 & E300 if interested).
- Using contaminated water to mix with. I always used cooled (or warm) boiled water.
- One their salts is not what it claimed to be. Normally it is the most expensive ingredient, the potassium nitrate, is not what it says it is and is something else or "diluted" with something else.
- I once got this worry, after purchasing nitrate from Ebay, rather than my normal supplier. So I dissolved a measured amount (can't remember the gr measure) in 100ml of deionised water to give 25ppm. Both my test strips and dropper test kit read nitrate present and 20-30ppm. So was nitrate. Another test is to dry some nitrate solution on paper towel and do a flame test. It passed...great fun.
- Potassium sorbate only works as a preservative if the pH is low.
- So you lower the pH to about 4.5 with ascorbic acid.
- Too low pH or too and potassium sorbate does not work so effectively.
- Not needed for macros as salt levels too high to grow anything if using EI levels.
- When peeps have had mold on their macro/all in one, the reason have been:
- Missing out potassium sorbate and/or ascorbic acid as they are "E" numbers so must be bad. ( E202 & E300 if interested).
- Using contaminated water to mix with. I always used cooled (or warm) boiled water.
- One their salts is not what it claimed to be. Normally it is the most expensive ingredient, the potassium nitrate, is not what it says it is and is something else or "diluted" with something else.
- I once got this worry, after purchasing nitrate from Ebay, rather than my normal supplier. So I dissolved a measured amount (can't remember the gr measure) in 100ml of deionised water to give 25ppm. Both my test strips and dropper test kit read nitrate present and 20-30ppm. So was nitrate. Another test is to dry some nitrate solution on paper towel and do a flame test. It passed...great fun.
- The micro is degraded by light (an higher temperatur), the iron especially unchelates, especially at higher pH, and precipitates out of solution to become plant bio non available.
- I used to mix up 2 litres or ferts at a time, never suffered mold, odd floating film on surface of ferts occasionally, but plants grew and were deep green so was working.
Its never too late M8, what do you nomaly dose for E202 & E300 in your dosing bottles?
I use to get mold in mine, but had very hard water, I always boiled/cool it for ferts, but maybe water was still on the hard side so slightly higher pH - but never tested the pre boiled water water
MrClockOff
Member
I have always used Spotless Water for prep as it’s DI. Have never boiled it before use and my fert containers were just rinsed. Nothing would grow in macros or micros during those 3 weeks except that thin layer of black stuff inside the feeding line. I didn’t care about it until recently when I went on holiday and on my return found that macros has been clogged and my plants looked starved. So I started looking into solutions. With the routine I had adding suggested amount of ascorbic acid and potassium sorbate made it even worse as now I managed to grow white fluffy stuff on the surface of ferts. But since a few tweaks I have mentioned above I fixed my issues.
Which is probably why they was clear of mold. I read around and found four weeks was fine for DIY ferts, any longer and the chances of mold increase, which is why in the IFC we put in the four week shelf life when making ferts. The shelf life was for the active fert containers, ones that had been made and stored in a cool dark place are fine - I use to use a freezer I had room in
