Question on RO & Rain Water

[gr865]

Question

I use RO or Rain water for everything, my tap water is over 800 ppm. I run coco DTW, so before I add any nutes I add 1 gram Epson and 1 ml Cal/Magic per gallon. That will put me in the 120 ppm/0.24 EC range then I begin adding my nutes.
I am in the final week of flower so adding the RO with the Epsom and C/M at the same 120 ppm rate and no nutes to my rez with the existing nutes, basically just lowering my ppm until they they get close to the 120 ppm of the RO. I am using about 2 gallons a day, so thinking just add two gallons to lower the ppm/EC gradually over the next week to 10 days.
My question is, should I continue adding the Epsom and C/M all the way to finish or run straight RO at some prior finish?

GR

 

[Bonsaiweed]

Question

I use RO or Rain water for everything, my tap water is over 800 ppm. I run coco DTW, so before I add any nutes I add 1 gram Epson and 1 ml Cal/Magic per gallon. That will put me in the 120 ppm/0.24 EC range then I begin adding my nutes.
I am in the final week of flower so adding the RO with the Epsom and C/M at the same 120 ppm rate and no nutes to my rez with the existing nutes, basically just lowering my ppm until they they get close to the 120 ppm of the RO. I am using about 2 gallons a day, so thinking just add two gallons to lower the ppm/EC gradually over the next week to 10 days.
My question is, should I continue adding the Epsom and C/M all the way to finish or run straight RO at some prior finish?

GR

My opinion (not worth much)

I would stop. 7 days isn't a long time and will allow the plant to use up any left in the coco.

I find it interesting you are measuring in weight and volume. I measure everything in volume.

Just an observation..... like I said not worth much. I'm a noob.

 

[gr865]

@ Bonsai,
Yes I use Epsom which is a dry product and Cal/Magic which is a liquid. If I were to measure it in volume it would be about a 1/4 tsp of Epsom, but I like being more percise and a jewelers scale gives me that.
I use to use a kitchen scale but it was so damn off.

 

[Weaselcracker]

Greetings grow rainwater user. Rainwater is all I've used for the last ten years.
I add Calmag (Botanicare) to my water as a base- to about 150-200 ppm. I don't bother to measure carefully - but it's around 4 ml/gallon.
I use this base for everything except clone cuttings. It also works as a mild veg nute due to the N content. Small seedlings just get this rainwater/calmag mix for food. Calmag has almost as much N as my regular veg nute.
For the last couple weeks, or however long it takes to finish- I skip the calmag and use water only- and let them ripen their buds and yellow their leaves on their own. I think pretty much all nutrient schedules will tell you the same thing - to discontinue all nutrients and just stick with water only at the end.
Sometimes I do keep feeding plants right through to harvest. But then I feed 2-300 ppm of PK flowering nutes. Definitely not Calmag with all that N in it.
I'm not a big fan of Epsom salts because they're so strong. There's enough magnesium in the Calmag - in the correct proportion. I've never had a mg deficiency as long as I feed with calmag.

 

[gr865]

@ Weaselcracker
You so right on buffering to 120 to 150 prior to adding nutes. It has work the best for me on both rain and RO water.

I believe it is all in the measure, 1 gram of Epsom is a very small amount.
I have had Mag issues so I feel safe with Epsom.
But don't you just love what rain water does, my ppm's are less than 10 on average, pH is around 6.6, industrial area. But it is clean as can be.

 

[Weaselcracker]

I'm far away from any industry and my rainwater ph is 5.6. Ppm is zero or at least as close to that as my meter will show. I look at the ph value as meaningless though -given that the ppm is so low. A tiny drop of acid/base will shift the rainwater drastically. Therefore the reverse applies, and the ph of the rainwater isn't going to affect my growing medium to any worthwhile amount.

My caution around Epsom salts comes from the amount I commonly see used. I see people all the time recommending 5ml ES per gallon.
Well 5 ml of Epsom salts in a gallon of rainwater - bumps it up from zero ppm to right around 500 ppm!
Meanwhile, the recommended 5ml/gallon of Calmag amounts to less than 50 ppm of Mg, and I've never had a Mg deficiency using that amount. So I cringe a bit when I see people using ten times as much.
Still- I don't see people having Mg overdose issues so it must be hard to OD on.

 

[gr865]

I'm far away from any industry and my rainwater ph is 5.6. Ppm is zero or at least as close to that as my meter will show. I look at the ph value as meaningless though -given that the ppm is so low. A tiny drop of acid/base will shift the rainwater drastically. Therefore the reverse applies, and the ph of the rainwater isn't going to affect my growing medium to any worthwhile amount.

My caution around Epsom salts comes from the amount I commonly see used. I see people all the time recommending 5ml ES per gallon.
Well 5 ml of Epsom salts in a gallon of rainwater - bumps it up from zero ppm to right around 500 ppm!
Meanwhile, the recommended 5ml/gallon of Calmag amounts to less than 50 ppm of Mg, and I've never had a Mg deficiency using that amount. So I cringe a bit when I see people using ten times as much.
Still- I don't see people having Mg overdose issues so it must be hard to OD on.

When I add a true gram of Epsom, measured with a jewelers scale, it increases the ppm of my RO or Rain water to 67 ppm, my combined ppm with Epsom and C/M is around 140 or so.
Running coco I have had many Mag issues, not as much now that I switched to Canna Coco, but still an Issue.
I am sure you can OD on mag but the amt I use has not caused any issues to date.
I have never seen Epsom in liquid form.

GR

 

[Old Salt]

Question

I use RO or Rain water for everything, my tap water is over 800 ppm. I run coco DTW, so before I add any nutes I add 1 gram Epson and 1 ml Cal/Magic per gallon. That will put me in the 120 ppm/0.24 EC range then I begin adding my nutes.
I am in the final week of flower so adding the RO with the Epsom and C/M at the same 120 ppm rate and no nutes to my rez with the existing nutes, basically just lowering my ppm until they they get close to the 120 ppm of the RO. I am using about 2 gallons a day, so thinking just add two gallons to lower the ppm/EC gradually over the next week to 10 days.
My question is, should I continue adding the Epsom and C/M all the way to finish or run straight RO at some prior finish?

GR

I'm using RO water for a coco grow that's now days away from harvest. It's my first grow for what it's worth. I've basically used GH Flora Series nutrients at 1/4 the recommended strength, including CaliMagic. For the last week to 12 days all I'm using is FloraKleen, and adjusting the pH to 6.1.

I use a luggage / fish scale (0-10Kg/5gm 10-45Kg/10gm) to measure water volume greater than 3 liters. Up to 3 liters I use an accurate 3Kg / 1gm scale. A jeweler's scale (100gm/0.01gm) is used for dry KoolBloom. I do have calibration weights for my scales to ensure accuracy. Oral syringes from 1ml to 10ml are used for liquid nutrients. I mix 16l at a time for four plants, which lasts four days, or a seven day supply of lesser volumes.

My grow seems to be OK. The harvest will tell the tale.