Water quality question

[Captain hardcore]

Hi peeps. My water is classed as hard and reads .5 ec and 7.6 ph from the tap, though it is very low in magnesium for hardwater according to the water authority report. Main details from report are-

Calcium 68mg/l ca
Magnesium 9mg/l mg
Nitrate 6 mg/l NO3
Phosphate 1.6 mg/l P
Sulphate 20 mg/l SO4
Alkalinity 167 mg/l CaCo3
I was wondering if I could just add a little epsom salts to bring the Mg levels up and use that as it is. Or do a tap water/ro mix though are the Mg levels already too low for this option?

 

[Bruce Campbell]

Typically, I try to manage K:Ca:Mg in a 4:2:1 ratio. So, adding Mg is only half of the equation for balancing the Ca in your tap. Overall, it also depends on whether you're doing an organic/soil grow vs a mineral salt fertilizer grow, if you're planning to fertigate each time (e.g., coco), alternate fertigate/irrigate, etc.

I grow in peat, fertigate each time, calculate out my elemental concentrations, and adjust my feed amounts to balance my overall K:Ca:Mg. Here's a how-to I wrote up walking through the math:

https://www.autoflower.org/threads/how-to-calculate-elemental-ppms.85531/

I'm currently using Megacrop 2-part with RO water b/c their formula didn't give me any easy way to offset the Ca from my tap and stay well balanced, but there are other solutions.

For reference, my tap is about 40 ppm (mg/L) Ca, and I usually see about 160-240 ppm overall K in vendor feed schedules.

 

[Captain hardcore]

Typically, I try to manage K:Ca:Mg in a 4:2:1 ratio. So, adding Mg is only half of the equation for balancing the Ca in your tap. Overall, it also depends on whether you're doing an organic/soil grow vs a mineral salt fertilizer grow, if you're planning to fertigate each time (e.g., coco), alternate fertigate/irrigate, etc.

I grow in peat, fertigate each time, calculate out my elemental concentrations, and adjust my feed amounts to balance my overall K:Ca:Mg. Here's a how-to I wrote up walking through the math:

https://www.autoflower.org/threads/how-to-calculate-elemental-ppms.85531/

I'm currently using Megacrop 2-part with RO water b/c their formula didn't give me any easy way to offset the Ca from my tap and stay well balanced, but there are other solutions.

For reference, my tap is about 40 ppm (mg/L) Ca, and I usually see about 160-240 ppm overall K in vendor feed schedules.

Thanks for the reply dude.
This is my first auto grow and a steep learning curve already. Im currently using biobizz lightmix alongside canna terra nutrients in standard pots with a feed, water, water, feed. Though for my next run I would like to use the lightmix in autopots and possibly go organic though I feel it may be best to keep it simple for a couple of runs. I understand water quility is very important and probably the place to start when constructing a plan. With that water quility would it be better to go with ro and calmag?

 

[Bruce Campbell]

Because you're alternating feed and water, I would not use tap in that situation. The tap Ca added on the water only days will likely unbalance your nute levels, eventually causing a buildup that would lead to a lock out.

Here's the RO system I have:
Amazon product

But, you really only need the sediment and charcoal filter cartridges to get you 90% of the way to pure water.

As far as calmag, you sometimes need it with RO water, sometimes you don't. Whether or not, and how much, depends on the K:Ca:Mg levels in each brand of feed...which is why I always calculate out the elemental ppms.

 

[St. Tom]

Hi peeps. My water is classed as hard and reads .5 ec and 7.6 ph from the tap, though it is very low in magnesium for hardwater according to the water authority report. Main details from report are-

Calcium 68mg/l ca
Magnesium 9mg/l mg
Nitrate 6 mg/l NO3
Phosphate 1.6 mg/l P
Sulphate 20 mg/l SO4
Alkalinity 167 mg/l CaCo3
I was wondering if I could just add a little epsom salts to bring the Mg levels up and use that as it is. Or do a tap water/ro mix though are the Mg levels already too low for this option?

@Mañ'O'Green is are nutes guy and will be able to assist you but he wont log in till later

 

[Mañ'O'Green]

@Captain hardcore Welcome to AFN Your water is a little too hard for most nutrient lines. I would blend it with RO/DI down to 100 PPM. Weather or not to add Epsom salt depends on the nutrient line you are using.

 

[Captain hardcore]

@Captain hardcore Welcome to AFN Your water is a little too hard for most nutrient lines. I would blend it with RO/DI down to 100 PPM. Weather or not to add Epsom salt depends on the nutrient line you are using.

Thank you for replying and for the warm welcome
So does it matter what the mineral content of those 100ppms are? Are those ppms purely to create a buffer? I thought producers like canna made formulas based on the assumption of certain levels of ca and mg being present in tap water. A quote from canna-
"Bad water (EC>0.5) contains mostly sodium and chloride. These two elements can block the uptake of beneficial nutrients and become toxic to your plants. With a Reverse Osmosis (R.O) filter, you can remove both of these elements. Simply making a mixture of bad water and R.O water to an E.C of 0.4 will result adequate bi-carbonates to stabilise pH levels, but the calcium and magnesium levels will be too low. Make a mixture of R.O and tap-water until you reach an E.C of 0.2 and then add CANNA CALMAG AGENT until you reach an E.C of 0.4."
Am I relying on the soil and nutrients providing all the minerals I need rather than any mineral content in the water?
Im currently using lightmix and canna terra, am I likely to need to add epsom salts to this?
I found a ppm value for terra flores at full strength 125N 44P 167K 40mg.

 

[Bob's Auto's]

"Bad water (EC>0.5) contains mostly sodium and chloride. These two elements can block the uptake of beneficial nutrients and become toxic to your plants. With a Reverse Osmosis (R.O) filter, you can remove both of these elements. Simply making a mixture of bad water and R.O water to an E.C of 0.4 will result adequate bi-carbonates to stabilise pH levels, but the calcium and magnesium levels will be too low. Make a mixture of R.O and tap-water until you reach an E.C of 0.2 and then add CANNA CALMAG AGENT until you reach an E.C of 0.4."

What a sales pitch from those Canna guys. First they tell you to dilute the water so there's less calcium in it and then you should use their product to add the calcium back to the solution...
I think it's time to start a thread to teach people how to make their own nutrients. It's much cheaper ánd you can add the values from your tap water into the calculation. Perfect all the time from the get go

Btw, a warm to AFN brother. As you've might have noticed we're a fun family to hang out with. So much knowledge is stored here, you won't find it anywhere else ♥ ♥ ♥

 

[Mañ'O'Green]

@AutoBobje It looks like they are doing something to sell Cal-mag but in reality it makes perfect sense to start with zero instead of an unknown mixture. Like @Captain hardcore points out it could be high Sodium making up the 100 PPM of the starting water. I concur with mixing your own and I am working on that starting with GreenLeaf Mega Crop 2 Part.

Tutorial - A word on Nutrients

The proper use of “salt” based fertilizer to grow Auto Flowering Cannabis. Salts: Natural and man made any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation. Learning how to use salt based...

www.autoflower.org

So if you are going to start with RO water then add 50PPM of Cal-Mag before you mix your nutrients. Many EC meters do not read below 50PPM so you need to add slowly until it registers on the meter. Pay attention to how much it takes and then the next time will be faster to just start with that amount.

Bio-Bizz Light Mix will need regular fertilizing after the firs couple of weeks.

 

[Bob's Auto's]

@AutoBobje It looks like they are doing something to sell Cal-mag but in reality it makes perfect sense to start with zero instead of an unknown mixture. Like @Captain hardcore points out it could be high Sodium making up the 100 PPM of the starting water. I concur with mixing your own and I am working on that starting with GreenLeaf Mega Crop 2 Part.

Tutorial - A word on Nutrients

The proper use of “salt” based fertilizer to grow Auto Flowering Cannabis. Salts: Natural and man made any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation. Learning how to use salt based...

www.autoflower.org

So if you are going to start with RO water then add 50PPM of Cal-Mag before you mix your nutrients. Many EC meters do not read below 50PPM so you need to add slowly until it registers on the meter. Pay attention to how much it takes and then the next time will be faster to just start with that amount.

Bio-Bizz Light Mix will need regular fertilizing after the firs couple of weeks.

I guess I'm lucky then. I can see the exact parameters of my tapwater. For some substances even to PPB.