Cal Mag & Distilled Water

[Tedmarx38]

I've read the other posts on this but questions remain, perhaps because my situation is a bit unique. I have a spring-fed well that produces water that's virtually distilled, and therefore has very little mineral content. It's also high in ph, like almost 9.

Following my Bloom City Cal Mag's directions of about 1 tsp/gallon does bring the tds up, but only to about 350. Ph remains around 7.3 after this is added, so I've been supplementing with citric acid powder to reach 6.5-6.8. For feeding I use Jack's 10-30-20 twice a week.

My question: would I do better to use more cal mag to get the tds higher, which as an added benefit lowers ph as well? With each indoor grow, and I'm on number 5 now over the past two years, the plants look great with the above approach until the mid flowering stage, when I always start seeing brown/rust coloring in the leaves which would be indicative of deficiencies in calcium, manganese and so on.

Thanks

Spider Farmer sf-2000 led 200 watt
Fox Farms Ocean forest soil
Temp range 67 dark, 84 light
20 on, 4 off
Spring water ph 8.7 corrected to 6.5
TDS raw is about 100

 

[Peat Phreak]

200ppm calcium and 75ppm magnesium is what I use without issues.

What is your media? What total nute ppm do you feed at peak demand? What is the ppm of the water before additives?

 

[Peat Phreak]

And why are you only using 10/30/20 twice a week? It contains almost zero calcium and sulfur. It also has way too much P and not enough N. Do you use that nute mix for the whole grow or only bloom?

https://d2j6dbq0eux0bg.cloudfront.net/images/13252146/765506639.jpg

The ammonium to nitrate blend is 50%. This reduces THC and actually harms the plant.

 

[Tedmarx38]

Thanks. I forgot to add the other details but put them in above - will append below too. I do sometimes use the nutes at either higher levels or more frequently based on soil test - last one showed them all being in the acceptable range. I've seen others recommend this product (jack's blossom) but am open to other suggestions.

Spider Farmer sf-2000 led 200 watt
Fox Farms Ocean forest soil
Temp range 67 dark, 84 light
20 on, 4 off
Spring water ph 8.7 corrected to 6.5
TDS raw is about 100

 

[Peat Phreak]

Then to answer your original question, you are using just the right amount of cal mag and adding more cal mag would not decrease pH unless the cal mag is acidified.

The nute mix still contains almost no sulfur. The plant needs sulfur.

 

[Tedmarx38]

Then to answer your original question, you are using just the right amount of cal mag and adding more cal mag would not decrease pH unless the cal mag is acidified.

The nute mix still contains almost no sulfur. The plant needs sulfur.

Thanks. A quick check if deficiency symptoms suggests this could be an issue. I have Neptune’s Harvest seaweed solution and it looks like it provides some of that. I’ll give it a try. Haven’t used it much.

 

[Peat Phreak]

Seaweed does not contain enough S. Your cal mag might have some but still not enough.

The necessity for S is significant. You might still have some left over in your soil. How much remains in the soil is a mystery. That is why I don't grow in soil.