Backyard Aquaponics
A place to discuss aquaponics

Recently read an article attesting to benefits of Potassium Hydroxide for plant growth. Any opinions on this as additive to system?

My new system's plants are looking tired at the edges for some plants, carrots dying, others are slow and not fruiting (tomatoes especially) and PH is sitting at around 8 and perhaps not unlocking enough nutrients. Are additives a good idea generally to help out in the early stages?

Does the fish food (commercial stuff) provide all the nutrients needed by the plants?

Any comments are much appreciated.

Oh and system is currently PH 8.0, Amm 0.25, nitrite 0, nitrate 80.

with a ph of 8.0, you probably are getting some nutrient lockout.. seasol with chelated iron is usually suggested as a fish safe "additive"
a quick search suggests that Potassium Hydroxide is a mutagen... i'd avoid it!

Potassium Hydroxide... while providing a Potassium boost that flowering/fruiting/seeding plants require....

Is a strong base... a pH buffer that would raise your pH further... compounding your lock out problems....

If you need a Potassium boost at your current pH level... bury some bananas in the grow bed...

Generally, a good quality fish feed will contain all the trace element provision you require.... providing your pH is within the range for uptake....

And, no... it's not a good idea in general to be in the mindset of adding things to your system... beyond addressing specific problems....

Maxicrop, or Maxicrop + Iron... will provide the trace elements you need... and is fish safe...

Thanks guys. Like the banana idea but will look into the maxi crop too.

If you have to add potassium, probably better to use Sulphate of Potash (SOP). Muriate of potash (MOP) is no good given the chloride you are adding. SOP is the most commonly used potassium based fertilizer in the horticultural sector. The sulphur in the SOP is good for S hungry cruciferous vegies like broccoli, kales, cabbages, rocket etc.

All true Santalum... as far as horticulture goes... and the obsession with phosphate based fertilisers....

But loading a recirculating system ... like AP... with phosphates... will just promote an algael bloom...

There are other, better means of providing the Potassium requirements in AP.... as listed above...


On another note... the chloride from a compound such as muriate of potash... isn't all bad in aquaponics either....

As... similar to salt... the chloride promotes blood osmotic balance...to mitigate against nitrites.. and slime coat production...

.... mis-read the above as monopotassium phosphate...

No matter... sulphate of potash... has a similar possible detremental effect... raising sulphate levels... which can cause plant problems...