Backyard Aquaponics
A place to discuss aquaponics

I'm looking for water testing for specific nutrients.
Namely potassium and magnesium.

I've found this product:
https://www.saltwateraquarium.com/saltw ... -nutrafin/
It covers phosphorus, calcium, hardness, and iron.

It almost seems like magnesium is included in the hardness testing, but I don't understand how that works.
"The hardness (calcium and magnesium concentration) of water can be approximated with a home-use water testing kit, or can be measured more accurately with a laboratory water test."

I could in theory assume potassium is my problem if everything else tests well and I have these problems:
"Symptoms being cupped or puckering of leaves. This is seen in the older leaves first and may also show up as marginal chlorosis. Leaves wilting even when the temperature is normal can be a symptom due to stunted root growth. Look at using potassium sulfate for supplemental corrections."

HERE ARE MY QUESTIONS:
How do I test magnesium with the linked kit?
Do I need to worry about potassium, or should I just dose potassium on a schedule and forget about testing it?

I mean does anyone have any tips for water testing in general?

I've been flying by the seat of my pants on foliar sprays and iron dosing.

I have calcium chloride i do as a foliar spray, iron chelate I weigh and add to the sump, and ascorbic acid I use to balance my ph very slowly by adding it to the sump.

I also have kelp meal (ground seaweed 1-0-2) but I'm unsure how to dose this as its not a pure chemical. Apparently adding it directly into the system is a bad idea since it rots and uses oxygen.
It has been said that its good for potassium, but I find no concrete answers on it online.

I recently bought some potassium sulfate to deal with potassium deficiencies.

I still don't know if I should be testing the K levels, dose on a schedule, or wait until I see deficiencies.

So now I have these materials available for nutrient deficiencies.

potassium sulfate (for potassium)
ascorbic acid (removes chloramine and hypochlorites from water additions as well as pH down)
calcium chloride (for calcium)
epsom salt (for magnesium)

Is there any other mineral I should add to my arsenal to tackle nutrient deficiencies with my testing?

Good questions. I hate to see this unanswered, but I don't have a good answer for you, except if you are using quality fish feed most nutrients will be provided. Don't make a lot of extra work unless you have evidence there is a problem. A new system with small fish will not support many plants, but as the fish grow and the feed increases there will be more nutrients available.

I have two systems and I add iron regularly (monthly, 11% DTPA). I also maintain (twice a year?) 1.5 ppt salt which is a mixture of NaCl, KCl and MgSO4 (Epsom salt). Once in a while (3 or 4 months?) I will add some Maxcrop powdered seaweed and some rock dust (azomite?) mostly to make me feel better. I'm not sure what it does. I have strawberries in one growbed that look iron deficient, but the next growbed in the same system they look fine.

Give things time to stabilize. Also pH will affect available nutrients so be sure you are in the 6.5 - 7 range if possible.

https://docs.google.com/spreadsheets/d/ ... sp=sharing

I made a master testing doc. It needs some stuff added to it but it has most of what your asking for and then some

Wow, that's a lot of research. A very helpful document. It also shows that sending water out for comprehensive testing is not a bad value. I think it costs $50 per test around here.