When diluting hard water with RO is extra magnesium via epsom salts typically required?

[ice minus]

Hi all, greetings from rural Waterloo region, ON!

I live in a part of the province that feeds a lot of the rest of our province. There are farms and fields in every direction that as far as I know do just fine with the regions tap water.

But this being said -- it's extremely hard out here. Around 330 PPM from the tap currently.

I saw in another thread that target PPM for cannabis is somewhere around 100, so I use 10L RO to 5L Tap and this puts me right around 100-115PPM.

My question is this: without knowing the exact concentrations of calcium and magnesium in our tap water (I've checked the regions website, sadly they only test for heavy metals and lead), and knowing that we have extremely hard 330PPM tapwater diluted down to around 115PPM with RO, would supplementing additional magnesium be required with epsom salts?

I just picked some up after seeing conflicting forum posts online and am still unsure on this

Big thanks again for any advice, cheers!!

 

[SuperFarang]

Hi

330PPM isnt "very hard"

if you start from RO water you will need to add some tap water to buffer the solution and increase the ph after adding the nutrients

in this case it does not matter if it contains calcium and magnesium or only calcium
because these two elements are trapped as bicarbonates in the water, thus not assimilables

this means you will have to add some calcium nitrate (around 50ppm) and possibly some magnesium sulfate (but it really depends how much your nutrients formula contains of MgO)

tap water also contains trace elements like Na and Cl. they are totally stripped by RO filtration

in my experience starting with filtrated water will give average results compared to hard water treated the right way

the best way to proceed:

-get some nitric acid (38%)

-lower the ph of your water at the desired value (around 6 to 6.5). the acid will break the bicarbonate bonds and yield calcium nitrate (and magnesium nitrate if you have mag. bicarbonate in you tap water)

-add your nutrients. PK boost first. then part B. last part A

should get around 1.8-2.0mS total ph 6

if it grows slow and after a week you start to see some yellowing between veins of fan leaves that probably means you grow in a calcic area (not dolomitic) with close to zero magnesium
in this case add 40 ppm of magnesium sulfate

 

[Boo]

remember, RO strips away all elements in the water...

 

[ice minus]

I was hoping to make use of the natural calcium and magnesium in the tap water that's naturally occuring

I have this stuff for pH down

TNB Naturals Dry Down 1lb https://a.co/d/ehUDr7v

And can bring it to 6.5 as needed, but sadly I will STILL need to use a calcium solution ? Bummer dude I thought my water already would have plenty

Thank you all for replying

 

[Boo]

Calmah for the win… it brings good level of calcium and magnesium into your feed water…

 

[PadawanWarrior]

I was hoping to make use of the natural calcium and magnesium in the tap water that's naturally occuring

I have this stuff for pH down

TNB Naturals Dry Down 1lb https://a.co/d/ehUDr7v

And can bring it to 6.5 as needed, but sadly I will STILL need to use a calcium solution ? Bummer dude I thought my water already would have plenty

Thank you all for replying

I wouldn't add Epsom unless you're sure you need it. Sounds like a decent plan to use 2/3 RO and 1/3 tap or 1/2 and 1/2. Also that TBN Dry Down is probably just citric acid which is pretty cheap.

 

[ice minus]

I wouldn't add Epsom unless you're sure you need it. Sounds like a decent plan to use 2/3 RO and 1/3 tap or 1/2 and 1/2. Also that TBN Dry Down is probably just citric acid which is pretty cheap.

Do you have a pH pen or drops that you recommend? I don't trust mine, it disagrees with the drops, and then the drops are kind of hard to read..

pH is honestly driving me nuts, my most hated part of the hobby!!

 

[PadawanWarrior]

Do you have a pH pen or drops that you recommend? I don't trust mine, it disagrees with the drops, and then the drops are kind of hard to read..

pH is honestly driving me nuts, my most hated part of the hobby!!

If you're in soil like I'm guessing since you're talking about natural pH down there's not usually a need to mess with pH. My well water is around 7.8 and I don't mess with adjusting it for my soil.

 

[ice minus]

Indeed, I am using Black Swallow Living Soil KIS Mix (not actually doing living soil though, just organics and using it as super soil).. there is SO MUCH conflicting information on this subject, for every guy who says they don't pH there's another guy who says it's a must

And just like yours, mine is around 7.8 out of the tap!!

I thought I had to bring it down to 6.5 so it can naturally take up the elements inside my mineral rich tapwater

 

[PadawanWarrior]

Indeed, I am using Black Swallow Living Soil KIS Mix (not actually doing living soil though, just organics and using it as super soil).. there is SO MUCH conflicting information on this subject, for every guy who says they don't pH there's another guy who says it's a must

And just like yours, mine is around 7.8 out of the tap!!

I thought I had to bring it down to 6.5 so it can naturally take up the elements inside my mineral rich tapwater

It is living soil. That just means it's alive with microbes and stuff. It doesn't necessarily have to have worms and other critters to be living. Those microbes will adjust the pH for the most part so you don't really need to worry about it. I never adjust water pH and I've been using the same soil for almost 6 years now.

 

[troutman]

Kitchener/Waterloo area is nice and I got family there.
I'm about 4 hours North.

Cheers

 

[Dime]

I'm on a well and my water is a lot higher than that,at 330 you can filter that in half. You can get a water analysis done at a place that sells or rents purification equipment and tell you exactly whats in your water,my municipal office will send mine away. I just run a double filter system which takes it down to 160,and the treated water ay my neighbours is 140.If you are saying your feed is 115ppm plus the solids in your source,you can buy GH 3 part for hard water and run it. Your RO should take it down to more than that.

 

[greencalyx]

I can only speak of my experience. Your tap water may be very different than mine as far as mineral ratios are concerned.

I also have very hard water (425+ppm). I dilute my tap water 50-50 with distilled (from dehumidifier). And I find that I still need to supplement Mg.

My city does not give mineral levels. I can only assume there is not much Mg in my tap to begin with and the hardness comes mainly from Calcium

 

[Creeperpark]

The problem with not knowing how much calcium and mag are in the tap water is the cal-mag ratio could be off. If it were me I would only use RO fortified with a little cal mag. That way you would have the right starting ratio set in the beginning. Mixing tap water with RO can work if the ratio is in the right portion, but not knowing the ratio could come back and bite you on the ass later in flowering. I would only use RO with cal mag with a starting ppm of 120 for any indoor grow.

The other way is to mix enough tap with RO with a starting ppm of 120 and see what it does. This will be harder to get dialed in but it can work if you watch the pH closely. The best way to watch this formula is by watching the pH of the intake water, and lastly the runoff. If the pH drops too low, then increase the tap water with RO water. If the pH rises then reduce the tap to lower the pH.

 

[Creeperpark]

Do you have a pH pen or drops that you recommend? I don't trust mine, it disagrees with the drops, and then the drops are kind of hard to read..

pH is honestly driving me nuts, my most hated part of the hobby!!

Testing and keeping an eye on the pH is a must in any indoor garden. If you have a good inexpensive meter and keep it calibrated and test all the liquids you will learn that keeping watch on pH is easy. Using regent pH drops are limited and not as helpful as using meters.

I have had an https://www.zoro.com/b/OAKTON/ for many years and found it easy to use and keep calibrated. Investing in a good pH meter will make the difference between success and minimal results.

 

[Douglas.Curtis]

I use r/o water exclusively. Cannabis is a dynamic accumulator, and even though most folks can't tell without lab tests, random 'stuff' in your tap water definitely impacts your end quality.

Remove it all and put back only the elements you need (not with tap water). Calcium acetate and magnesium sulfate are AWESOME and suuuper inexpensive, so you can definitely skip the 'bottled' products for your calcium and magnesium needs.

 

[PadawanWarrior]

Testing and keeping an eye on the pH is a must in any indoor garden.

He's using organic living soil so most likely he doesn't need to worry about pH. Not saying it's impossible for it to be off, but it's rare. My soils pH has only been off in one pot one time in 6 years and that's because I added a bunch of extra peat moss to it without adding OSF and then used a bunch of potassium sulfate which lowered it further. Not to mention it was also only 5 gallons of soil vs my other pots of 15 gallons so it was drying out more than you want with organics. So my $150 Bluelab meter has only really found an issue once so far for me in living soil.

 

[goingrey]

Do you have a pH pen or drops that you recommend? I don't trust mine, it disagrees with the drops, and then the drops are kind of hard to read..

pH is honestly driving me nuts, my most hated part of the hobby!!

When's the last time you calibrated your meter?

 

[SuperFarang]

I was hoping to make use of the natural calcium and magnesium in the tap water that's naturally occuring

I have this stuff for pH down

TNB Naturals Dry Down 1lb https://a.co/d/ehUDr7v

And can bring it to 6.5 as needed, but sadly I will STILL need to use a calcium solution ? Bummer dude I thought my water already would have plenty

Thank you all for replying

to use the calcium (and eventually magnesium) naturally present in your tap water you need to use acid
this will free the calcium ion from its bicarbonate and make it available to your plants

your ph down, it is formulated from phosphoric acid right ?
this will work but nitric acid (38%) is superior, as it will not form any precipitate

anyhow if you can't find any water analysis from your area (which would surprise me) it will be difficult to know how much calcium/magnesium is present in your tap

actually it can be very low because other elements naturally abondant in some regions (sulfates, chlorides, sodium...)also influence conductivity of the tap water

if they lack calcium, you will see rust spots on fan leaves
if they lack magnesium, you will get interveinal chlorosis on middle leaves

also

ph tester drops are reliable and economical
aim for a piss yellow(ph 6) to green/yellow (ph 6.5)

 

[ice minus]

I was offline for a day or two - I actually just came back from Black Swallow Living Soil this afternoon, picked up a few more bags of soil plus they got in the Blumat drip rings, which I just am about to try and install now!

I also got some Fish Hydrosylate which they whole heartedly recommended me

I will go over each and every one of these replies, just wanted to say big thanks again for all the responses!