what's a good starting EC for the water when using organic nutes in soil?

[Max Headroom]

i have access to rainwater @ ~50µS/cm and hard tapwater @ ~600µS/cm.
for the first time in a long while i'm using organic nutes. i like to keep things as simple as possible, so i only use a basic bloom product and nothing else. this time it's plagrons alga bloom.
even though they say on their website "you don't have to regulate the pH and EC value of nutrient solutions", i have questions about how much of that is just marketing bullshit.
i'm sure it'll make some sort of difference what the base EC of the water is.

any suggestions what EC the water should have?
(soil is light mix)

TIA!

 

[flylowgethigh]

Living soil (at least in my case) doesn't like EC. I change the water in my reservoir if the truncheon lights up at all. Usually from using epsom salt. I pH my tap water to 6.5 and add cal-mag ( plants are under LED), and while the roots are growing I also add aloe. Biggest thing I have found is keeping the soil moist enough for the ion exchange electrolyte to work. I have a single probe pH meter that will go way low when the soil is wet and the ions are exchanging - I call it sparking. It is probably a galvanic reaction that makes the probe work anyways. When plants are not doing well, the soil usually also isn't sparking. That has been a sign of being too dry.

 

[Growenhaft]

only with rainwater will you very quickly develop a calcium deficiency and most of the other trace elements.

a mixture of rainwater and tap water to an ec 0.45 is good starting water.

but rainwater is dangerous, it will bring animals into your growroom.

 

[Creeperpark]

I don't know what you are talking about, Growenhaft, because I only use rain water and nothing else. NO disrespect to you, but rain water is superior to most waters. The starting pH of rain is around 5.5 to 5.6 from carbonic acid filtered out of the atmosphere. The ppm of fresh rain water is between 7 and 26 ppm and perfect for starting the (CEC) in the root zone. The trick is, never let rain water hit the ground and only harvest "pure rain" out of the rain barrel. When rain touches the ground its not pure anymore and loses it capacity for Cation exchange. .

In organic grows one can supplement the rain water with a small amount (tiny pinch) of dolomite lime into the rain water bucket and bubble it and raising the ppm to around 90 to 120 ppm. If you have a good source of calcium in the organic super mix, you won't even need to supplement the rain water at all. I have used rain only, without anything added when the mixes were hot so to speak.

Now I'm using 8 mls of Cal-mag per 4 gallons of rain water with my synthetic grow starting at 126 ppm water! Here's a live photo of a rain water plant growing now.

I have only used rain water all the time and as long as I can remember.
In the hot dry summer when I can't get any rain water and used all I had up, then I use RO. However most of the time I can make it all the way through summer drought. The only reason I use rain is because it gives super results very quickly and boosts the Cation Exchange Capacity.

 

[Max Headroom]

a mixture of rainwater and tap water to an ec 0.45 is good starting water.

thanks, i'll aim for that by mixing the two sources.

 

[Growenhaft]

I don't know what you are talking about, Growenhaft

I'm talking about it being meaningless.
cannabis has an above-average consumption of all trace elements. they take rainwater, then add a high dose of cal / mag.
but what about all the other minerals in trace form? manganese, zinc, iron, boron, etc.?
they don't enrich that. I find that meaningless.

without disrespect, your image doesn't knock me off my feet.

rainwater, collected over the roof, draining the rain gutter into a rain barrel, includes the following items.
micro-plastic, atmospheric dirt and pollutants, residues from fertilizers and pesticides from agriculture, steam residues from glyphosate.
More dust and dirt over the roof, a lot of blown tire abrasion and pollen.
the roof itself as well as the downpipe also have a strong influence.
Small animals, mosquitoes, jumping tails, etc., are very quickly in the tank. therefore it is better to filter the rainwater.
but how high the damage caused by rainwater really is can only be clarified by a laboratory. is of course different from region to region.

The amount of rain and the duration also play a major role. impossible to keep constant conditions.
but that's just my opinion, i respect yours. tap water in a stale state will always be cleaner like rainwater in my region.
it can be different for them. therefore your statement is far too general for me.

 

[Creeperpark]

I've have used every kind of water known in Horticulture. I have worked in Big greenhouses and on large landscaping sites for many years, and have a lot of experience with Hydroculture. Today I only use clean rain water and get super results.