Potassium chloride the the water softener?

[hashbaz]

Someone else posted about problems with water softeners and it got me thinking, but I did not want to hijack their thread.

Water softeners work with either sodium chloride (salt) or potassium chloride. Sodium ions are bad for plants but we pay money to add potassium. So water softened with potassium chloride might be very beneficial.

In many houses, the cold water in the kitchen faucet is not softened. So when adding warm water, you get a mixture of hard and soft.

Here is my take on the numbers:

Using potassium chloride in your softener will contribute approximately 32 milligrams of potassium per 8 ounces of water for each 10 grains of hardness softened

link to source

32mg/8oz = 135ppm
10grains = 144ppm
Lets assume a water hardness of 200ppm (11dH). This would put 187ppm of potassium into the soft water.

I used my own hot/cold temps (143F hot and 53F cold) and desired temp of 78F. This gives roughly 75% cold/hard and 25% hot/soft.

Results: warm water (for water changes) has about 47ppm of Potassium.

It looks like partially softened water is a great option.

I've read that you can't overdose potassium but there has to be a point where it causes problems. How much is too much? Or is there anything I have overlooked?

[malkore]

I don't know if the leftover potassium is available to be used, but I do know that potassium chloride salt is better when you are stuck using softened water for water changes.

You should still add some epsom salt to replace lost Mg.

[czcz]

I've read that you can't overdose potassium but there has to be a point where it causes problems. How much is too much?

Tom Barr suggests 50ppm K as a ceiling is good practice. He says very high K dosing does not break anything. It is said excess K dosing blocks Ca uptake, and will lead to curled leaves.

For what its worth, I add a 3-4g nugget of dry KCl per 10gal weekly. (The nuggets are a PITA to break up.) Along with potassium from KNO3, I get near 75ppm K in high light, and I see no Ca deficiency indicators. All my med light and higher tanks do fine. My experience has led me to believe high K dosing leads to healthier plants, and I incorporate it into adapted EI.

HTH