How to mix RO water with potassium bicarbonate and calmag

I am looking for advice on mixing ro water using potassium bicarbonate for ph up and calmag for minerals.

The growing medium is Vic High supersoil.

I have always used tap water for the last 20 years but just moved and have well water now with 340 ppm. So I am switching to ro water.

I have done as much research as I can and have a slight idea on what to do but still have some confusion.

Information of general consensus seems to say a carbonate/bicarbonate is better for ph up and calmag should be 4 to 5 ml per gallon to get a 200 ppm.

So I did some experiments with mixing ro and different calmag levels per gallon to see how things came out.

1. I used the potassium bicarbonate first and raised the water ph from 6.2 to 6.5 which I always set my tap water for.
It took just a real tiny pinch of the bicarbonate crystals to raise the ph to 6.5. in 3 separate 1 gallon buckets filled with the ro water.

Bucket #1
I added 2ml of calmag and ended up with 190 ppm

Bucket #2
I added 3ml of calmag and got 230 ppm.

Bucket #3
I added 4ml of calmag and got 280 ppm.

All calmag inputs were measured with a graduated syringe.

Any advice helps.

Did I mix in the right order?

Why might my ppm be so high for 4 ml calmag then what others say they get?

When I add the calmag should I be more concerned about the ppm or the ml amount people have typically been using?

Thank you to everyone who wishes to contribute.


Why would

340 ppm’s isn’t that bad, do you know what comprises the ppm’s? You might not need Ca. I grow with water that’s 1400-2400 ppm’s, well water, you can darn nearly chew the water. Grows plants just fine.

FWIW, I use 650 ppm tap water as ph up.

No I don't know the make up of the water ppm. I just used a tds meter to get the ppm reading. Whatever is wrong it has caused a nute lockout in the two grows I have tried since using the well water.
I have been growing the same way with supersoil for 20+years without any issues at my last place. The only thing different is my water source so I am reasonably assuming that is where my problem is.
I use a par meter to set my lights distance, a ph meter to ph the water to 6.5, a moisture meter for watering, and a tds for checking the ppm.
My guess is a calcium buildup in the soil locking out the K.
In the last week I have flushed with RO and giving a potassium sulfate foliar feeding. I only used half the strength listed for the 0-0-50 sulfate which was 1/2 teaspoon. I am going to do another foliar feed but use 1 tsp of the sulfate plus I am adding in 1 tablespoon of Epsom salt. The lockout doesn't seem any better since the last foliar but it seems to have stopped getting worse.
So maybe the full dose of sulfate along with the Epsom Salt will make a bigger impact.

I did a lot of experimenting yesterday to determine exactly what amounts I need to add to the water.
What I came up with is:
In 1 gallon of RO I add, .35 grams of potassium bicarbonate for ph buffering and ppm comes to 90 ppm give or take a couple of points. Then I add 1.5 ml of calmag which brings the ppm to 200 plus or minus 10 ppm.
That will be all I plan on adding to the water since the supersoil should take care of the rest.
Well let me know what you think.

Maybe try the well water for a cycle and if it does not work go to ro?
RO is just a hassle. Get a water test done to see if there are major problems that make it unsuitable. High fluoride or sodium kill plants. Higher ppm is not a problem in itself.