Backyard Aquaponics
A place to discuss aquaponics

Wouldn't the plants just use/take up the sulphur , its use is well known in plant nutrition

Eco fung. $40/kg
pot. sulphate $1-$2/kg in a 25kg bag probably $10/kg from a garden centre . If you look hard enough you can even buy organic potash (same hole different label)

Hi Charlie,
Yes I am doing it for a long time already. I put around 1 liter fresh coconut juice in my growbed like every month.
I am in the Philippines and coco juice is as in throw away in the market. I just bring some bottles and ask them for free. My veggies are large and green especially my kangkong...more than enough for me...so i give the kangkong away to my neighbors.

Coco juice is $6 a litre here, kids like the fruit flavored ones.

Cool, thanks jetson.

Do you do it primarily for potassium?

Whats are the problems associated with an excess of sulphur? Some plants should absorb it to help lower levels(think cruciferous especially). I've just added 1tsp of sulphate of potash over the weekend and the difference in a few days has been astonishing. fruits suddenly growing properly (3 cucumbers popped out almost overnight) and flowers galore.

Couldn't go the potassium bicarb route as ph never drops low enough in summer due to the constant high ph of the top up water (topping up about 1/5th system vol per week).

Found this
http://www.ptno.ogr.ar.krakow.pl/Wydawn ... 701p08.pdf

suggests high sulphate does not effect tom growth at least. Not sure if it upsets the fish though...

Sulphates aren't really that great a problem for fish but can cause ademna in plants if overdone. What PH does your system run at matt? I see your on a potassium bender lately

yeah - normally 7.5 to 7.7 in summer - don't really want to add pot bicarb when it is that high and have got bad potassium deficiencies in all 3 systems.

Im in the same boat, took me years to naturally get down to 6.9 and Im always dubious adding things. Ive noticed over time that deficiencies are swings and round abouts, in most cases issues I see either effect only a small minority of plants or usually only for a short time so Ive kinda adopted a wait and see perspective. Doesnt mean its the right perspective but its less stressing.

Yeah I can see the value of that approach. That said my chillis, beans, zuchini, pumpkins, spinach were all showing signs of deficiency (to the extent that older leaves had severe tip burn/spots and were going totally necrotic) so was finding it pretty frustrating getting minimal produce from the system using the wait for it to self correct approach.


I don't understand what makes a mature (as in 2+ years) system ph drop though (compared to a 6 month old system for instance) - if we are always adding high ph top up water and the rate of feed (and therefore acidification from nitrification) are the same. My current understanding is that once the system is cycled, the ph drop will only be related to the amount of feed going into the system and the amount of buffer (in top water). I don't have the problem in winter as I don't add high ph top up water - Was struggling to keep my ph up from 6 then.

Am I missing something in my understanding of how the system functions?