Low calcium well water in organic grows

Hello all,

I'm lucky to have some pretty good well water. It comes out of the ground between 7 and 7.2. It has a low calcium content. Water is around 75-80PPM with most of that being calcium. I am currently growing indoors and using an automated halo system to water my plants as they are scrogged and hard to get to. I have a reservoir and a small pump to water as needed.

I am assuming that many in the organic community would probably just water as is.

This would be the first question--If I want to dial this in is this good as is?

I was originally adjusting my water"(per Ed Rosenthal) to get my PPM up to around 125 using Calmag. I was also PH'ing the water down to around 6.3. I noticed that the PH would quickly climb back up to the original level in a day or two.

Is there a way in the organic realm to get some more mineral content and stabilize the PH?
I know it matters less with living soil grows. I am inching my way in that direction, but not there yet.

Are there times in an organic grow when i might need to get my water to a lower PH? How best to do this?

I’d recommend dolomite lime personally, as it added calcium and magnesium to my medium when amended. The finer the granules/powder, the faster it’s available.
EDIT: plus dolomite lime has a neutral ph value of 7 so it will help raise low Ph values.

If you’re looking for an organic Ph down, Lemon juice is all organic, and as well as baking soda to raise Ph, I’ve heard of people using other things though like lime juice or vinegar (haven’t tried those)

Don’t ph the water; buffer ph w/ minerals in your mix directly...
I suggest adding D-lime too but you’ll need to wait until you amend the soil to add it in. You probably will need to continue giving soluble cal mag until your soil is recycled and amended a few times w/minerals. If absorbtion (ph) is an issue then hydrating Epsom salts could help; bubble a cup w/gal of water and serve. Should help buffer ph down slightly.
Adding composted eggshells helped me get off of cal-mag for good but it took about a year of amending with them to get there.
A fast easy fix for now could be crushed oyster shell flour which works great as a ph buffer when in the root zone. Add in a handful or two per container when you build your pots.
I like to use it in conjunction w/ a high N base layer like this: start w/ a combo of ewc and chicken manure mixed in with base soil in the bottom few inches of the pot...and then add in a hand ful (or two) of crushed oyster shell flour & swirl it around .. a sprinkle of myco and then drop the root ball on top and fill it in w/soil. It takes a while for it to break down but oyster shell is high in calcium and phosphor.

Green_Alchemist said:

I’d recommend dolomite lime personally, as it added calcium and magnesium to my medium when amended. The finer the granules/powder, the faster it’s available.
EDIT: plus dolomite lime has a neutral ph value of 7 so it will help raise low Ph values.

If you’re looking for an organic Ph down, Lemon juice is all organic, and as well as baking soda to raise Ph, I’ve heard of people using other things though like lime juice or vinegar (haven’t tried those)

Click to expand...

Thanks. If anything, I want my PH to be lower. I have some dolemite in my soil mixes

Richard Drysift said:

Don’t ph the water; buffer ph w/ minerals in your mix directly...
I suggest adding D-lime too but you’ll need to wait until you amend the soil to add it in. You probably will need to continue giving soluble cal mag until your soil is recycled and amended a few times w/minerals. If absorbtion (ph) is an issue then hydrating Epsom salts could help; bubble a cup w/gal of water and serve. Should help buffer ph down slightly.
Adding composted eggshells helped me get off of cal-mag for good but it took about a year of amending with them to get there.
A fast easy fix for now could be crushed oyster shell flour which works great as a ph buffer when in the root zone. Add in a handful or two per container when you build your pots.
I like to use it in conjunction w/ a high N base layer like this: start w/ a combo of ewc and chicken manure mixed in with base soil in the bottom few inches of the pot...and then add in a hand ful (or two) of crushed oyster shell flour & swirl it around .. a sprinkle of myco and then drop the root ball on top and fill it in w/soil. It takes a while for it to break down but oyster shell is high in calcium and phosphor.

Click to expand...

OK. Thanks! SO, for now, blow off any PH adjusting.

Would you be adding Calmag because of the low calcium in the water? Part of my reasoning was to bring up the stability of the PH. With that low of hardness, the PH moves all around. I have a bit of dolemite that has been in my soil for quite a while. I'm getting ok PH coming out after watering. Different from plant to plant, but the highest is around 6.5. Most of them are around 6.2-6.3

Ph in soil always moves around; that’s how you know it is active. Calcium is one of those things that is kind of hard to provide in a slow release form; there are only so many sources and those need to be decomposed in order to be absorbed. If the plants look healthy and green don’t worry so much about ph. Amending w/minerals is really all you can do besides giving soluble cal-mag until your mix is up to par. You are lucky to be on a well. My city tap water smells like a pool.

Your water is fine even with the little extra calcium. Like others have said, focus on your minerals, as your water ph doesn't matter assuming you have a proper buffer. I reccomend you stay away from Dolomite, this is a product meant for acres, not sqft, let alone gallons. Replacements for dolomite would be ag lime. However I would stay away from that as well, focus on oyster shell, in conjunction with crab meal/crustacian, cal-phos, and gypsum. This in my opinion is the ultimate ph/calcium mix.

foreverflyhi said:

Your water is fine even with the little extra calcium. Like others have said, focus on your minerals, as your water ph doesn't matter assuming you have a proper buffer. I reccomend you stay away from Dolomite, this is a product meant for acres, not sqft, let alone gallons. Replacements for dolomite would be ag lime. However I would stay away from that as well, focus on oyster shell, in conjunction with crab meal/crustacian, cal-phos, and gypsum. This in my opinion is the ultimate ph/calcium mix.

Click to expand...

I will definitely look into this as I put my next soil together. It’s a lot of stuff to learn, especially with so many different routes and opinions. I appreciate the info

Look into build a soil mineral mix. Especially if you want to take all the thinking work out. Also even better if some of these products I mentioned are hard to find.