Coco Peat Coir and dolomite lime

[Bluey]

Does anyone have intimate knowledge for using dolomite lime in coco as a cal/mag buffer/additive?

i have run into strife now with cal/mag deficiencies in coco. I can easily up the mag with epsom salts but it still leaves me short on cal.

I have zero EC water before nutes. I plan on using silica until about 4 weeks before harvest.

I want relative stable pH at the roots. My last cal/mag micro additive caused rising pH in my nute tank which likely translated to rising pH at the roots.

Any better solutions I can give a go for initial buffering and ongoing supplimenting?

[9fingerleafs]

I use calcium nitrate in coco. It's super soluble so don't try to amend the coco because it will dissolve in the first watering. Use it every watering. It's a great base nutrient for the first 100-300 ppm. The other nutrient I use it's called peters profesional the hight intensity discharge formula. It's the same as jack hydro in the USA. Many "complete" formulas come without calcium and nitrogen because they're meant to be used with calcium nitrate. Mix right before watering and keep in a tight seal container because it will draw water from the environment and become liquid

[Ckbrew]

I use GH Calimagic- calmag supplement for coco. Dose at 10ml/gallon for the initial soaking of the coco, then 5ml/G for the first few weeks of feedings. The binding sites on the coco must be saturated, otherwise the coco will bind the Ca and Mg so it will not be available to the plant.

[9fingerleafs]

Yes very true. It's called washing the coco. Leave soaking in hard water for 24 to 48 hours then rinse. Not all brand need to be washed. Only the generic bricks or sacks. Those canna, fox farms and other big brands come washed and ready to use.

Coco not only sucks calcium in those binding sites. But also dumps potassium in a "trade" cation exchange. So if not washed and flushed the already potassium rich substrate can create potassium toxicity preventing any calcium to be absorbed by the plant. A common mistake when this happens it's trying to flush the medium making a bad situation worse. What's needed it's to increase the EC with mostly calcium to feed the plant thru osmosis

[Ckbrew]

I'm familiar with the starting with the bricks thing. Gave that up after one year, my time is more valuable than that. I use Mother Earth coco/perlite 70/30. It is supposed to be washed and buffered, but i have found that it still needs to be saturated with calmag before using to avoid calcium issues in the plants.

[9fingerleafs]

Good to know. I've never tried mother earth. I use 250 liters a week so I buy in bulk non branded coco with no perlite

[Bluey]

Thanks very much for that input. Very valuable.

I'll run some testing on the stability of the pH with the nute solution mixed. I always drain to waste. I'll hit up calcium nitrate first with epsom salts, nutes and silica in a test solution and see what happens with the pH.

Quality of bud as measured by perceived effects is what I am chasing (another subject), but it is so subjective I find as there are way too many variables we cannot manage at all or even measure yet. I am trying to reduce the variables in the grow output by managing the grow better. Am I wasting my time chasing these outcomes indoors to achieve consistsnt perceived effects? I couldnt achieve this outdoors in 30 years.

I'm going to have to test the leachate (runoff) but previous testing of this did not produce accurate or repeatable results. I'm new to indoor grows so pH is an entirely different management requirement to my previous soil grows (almost zero issues), even using a syringe to suck up the first of the runoff. Basically this testing was not reflecting the pH at the roots as it was hugely variable and showing results at times that meant my plants should have been next to dead but they were healthy as. I suspect residual compounds were throwing this way out, perhaps not so much in the coco but on the surfaces of the pot/trays...just don't know.

First grow I was running off the nute mix to flush about 1/5 out the bottom each feed. Second grow I didn't bother with regular runoff each feed but only once or twice a week. Some weeks early in the grow, never. Both grows exhibited cal mag deficiency in 1 strain and I caused other problems across the whole grow trying to correct this with incompatible additives that caused fast rising pH in my nute tank on my second grow over a 3 week period in mid flower.

First grow I was running max EC around 1.4/1.5 and second grow around 1.6. I'll up my EC again across the whole timeline from mid veg to mid/late flower in this next grow but the leaf symptoms are clearly cal/mag related. Leaf burn was showing a bit last grow but not greatly or causing issues.

This grow I'm reducing the number of plants in the grow from 4 to 2 and will stick to one strain which should make management easier but I need to sort my cal/mag issues and be better prepared.

This issue is really the only problem I can see that is stressing my plants and reducing both quality and yield, probably not greatly as the last harvest is smoking great but I do know I can and have achieved better. I am aiming for quality. Yield is fine at about a pound a plant.

[9fingerleafs]

pH is hard to manage thru runoff. Just like you said. Many things get dumped by the plant. I like to control the pH going in and that's it. If you water often enough with full nutrient formula at the right pH eventually the pH will stabilize across the medium and runoff.

One thing is not talked about in begginer forums like this one is that the medium EC (inside the pot) needs to be much higher than the feeding values. Usually around 3 to 4 EC. This happens because the salts accumulate and it's not a bad thing. Of you water to runoff every single time the plant will show deficiencies in flower. But also if the ratio is not the right one an accumulation of potassium can lock calcium out of the roots. On the other hand, the decomposition of the coco fiber produces potassium available to the plant. But after a few weeks it decreases. So you need to increase the potassium ratio after mid flower. I like to use mono potassium phosphate (mkp) because it also improves bulking and accelerates flowering. It's the main ingredient in flowering boost formulas but you can get it very cheap off brand.

I have a small growing business, around 200 plant per year harvesting 4 plants a week with a continuous 32 plants flowering (harvest 4 and put another 4 to flower every week. 8 weeks = 32 plants) so I have very little room to try new strains. I've gone thru 35 strains or so during the last few years. And the strongest (most potent high) strain I have found is called descojack from delicious seeds. It's a cross between jack herrer(super silver Haze) and a mystery kush. I don't know if it's the haze but it's just more potent than all the others. So if you are looking for potency start with the right strain. This strain it's a big stretcher (over 6 feet high outdoors) and yields very very well. Big round buds with a very earthy smell.

One last thing. I'm guessing you are using a pH electronic wand to measure pH. I don't like them. They're just too sensitive and need calibration all the time and get you worrying about 0.05 changes. My advice is get some pH paper strips made for chemical laboratory reactions. Just aim for a pH 6. Paper strips, I swear to God, cheap and effective. Doesn't matter if the pH is 6.2 or 5.8. Try to ain at 6 and you'll be fine

[Bluey]

Growing sativas and a couple of hybrids. Not high in THC. This current jar has been one that slowly comes over you but it hangs around for some time. Body feeling is where it's at for me. This one's a 50/50 body mind...relaxing. Works spot on for chronic pain. I have a bad tooth and it works long term very well on the pain. I can sleep and function well.
Using an Apera PH60 and careful to vary the pH going in typically 6 to 6.25 in later flower, but I vary it every week. Can vary it more if needed but tend to mix a 5 to 7 days supply in the nute tank at a time. Temp of nute mix hangs around the 18 to 20⁰C mark. pH in the tank hardly moves, nutes are stable for that period unless my supplemental calmag is not compatible...argh, that was a fuck up.
I've just given the coco a good flush ready for its 3rd grow. Havent dosed it yet. Tossing up to give it a couple of full veg nute flushes or hot shots I think they call them and then just keep up a couple of teaspoons per gal of the epsom salts and I'll test some cal nitrate with that.
Climate is pretty well nailed re temps & humidity and operate on a pretty small air changeover in the room but its fine..strong breeze in the room, everything moving around nicely.