Backyard Aquaponics
A place to discuss aquaponics

There are a few different brands of "99% pure" phosphate on Amazon.

The one is claiming that it has 0-46-0 range while being called an enriched form of phosphate.
Guaranteed analysis 45% P205..a triple super phosphate...

Other brands are stating to carry a formulation of 0-3-0.

Should I go for the stronger brand and save by using much smaller doses?

Also I will be dosing a 350 gallon stock tank that the plants are hanging into with baskets.

I have no idea how much I should begin experimenting with as I have 4 pepper sprouts, 6 small tomato plants and one full fruiting tomato (cherry type). I hope to dose the water with nutes that my plants need now and then dose the top up accordingly with P and K with water change/evap replacement water.

The growth has slowed a lot. Most sucker growth has a rubbery feel that will pull off with almost taffy consistency if you pick it apart while some healthier leaves are curling and growing spindly. Tomatoes continue to grow on the main plant.. 32 to count..though I suspect I should have a lot more.

Are you sure there's a P deficiency?

I have never seen P deficiency & I don't think I've ever heard of it in aquaponics.

Trying to add all this stuff may cause problems with nutrients being locked out.


I really don't know sorry.Maybe someone who has dealt with P deficiency before can help or check the forum & see if there's anything.


Check the Nitrates,sometimes when there is too much the stem/branches go soft.And too much Nitrate might reduce the bloom stage.

What way are the leaves curling? (up or down) & what are you feeding the fish?

Usually what you'll get with the addition of phosphate is a really strong algae bloom and sometimes with that bloom you'll get a drastic reduction in oxygen in the water... that's the reason that there is a nationwide voluntary ban on phosphate based detergents here in the US since 1994. There should be enough phosphates in the feed so I wouldn't add any. Potassium and iron are the two most likely deficiencies in AP based on what I've seen here on the forum.

If the newest leaves are lighter yellow than the older leaves then it's an iron deficiency. If the older leaves are turning yellow around the edges then it's a potassium deficiency.