Grow Mediums autopot size and coco and PH levels - a theory

[lunarman]

Maybe for real instead of a theory.

I have an accurate 8 12inch PH probe that Waira and others recommend. It's not crap like the $5 ph probes. I think it's accurate enough. And instead of measuring PH runoff, you can measure the PH in the medium or at the roots basically. Which is where you want to read it.

I have found that with coco in the autopots the PH levels vary by depth. I think its fair to say there is the PH level of the feed, and there is the PH level of the medium. And with coco and the autopots and the bottom fed gravity system, the PH down at the bottom of the pot is going to be quite different than the top. And the accurate 8 is giving me readings that show this.

I recently precharged two regular size autopot with coco and PH'd water of 5.8. No plants yet. Measuring PH near the top is 6.8. Down at the bottom is 6.2. Big difference.

I may be wrong about this, but if PH is important during the seedling phase, you don't want to have the roots in a coco medium that is PH level 6.8.

I have no idea if this is important or not. I am pretty sure I've seen great autopot grows that were dropped right in the regular size pots and the PH levels and depth didn't come in to play and screw up the seedlings. But been detail orientated, I think there is something to be aware of here. And that is to start out in a smaller pot at first with coco ph'd right and you don't have to worry if the PH is too high.

 

[BII]

What type and brand coco is this - brick or loose; buffered or not; flushed/rinsed or not; etc.? Pure coco or perlite added?

Maybe, do more flushing of the coco? With nothing planted yet, can't hurt. Do a lot with tap/hose water and end with your final pHed feed pre-charge.

I would presume seeds, containing their own full nutrition for a while, are pretty tolerant of soil/water pH. Out in nature they certainly have to be pH-tolerant. Following the lead of others on AFN, I don't bother to pH tap water at 7.25 fed to seeds and small seedlings. I'm planting directly into my final Air-Pots containing 85/15 coco and perlite which has been thoroughly washed/rinsed and allowed to normalize (just let sit) for about a week before seeds are planted.

 

[KonopCh]

Ah man, you just overthinking...
Relax and grow.

 

[kushedy]

I'm making an assumption here but every time you top feed your plant (during first few weeks of establishing in the auotpot) with feed in the range of 5.5 - 5.8ph (for most users) you are helping to adjust the coco to the correct range. That's my best guess but bottom line whatever the coco ph reading is the system works & works quite well.
It would be more interesting to know how the coco ph changes over the course of a grow at varying depths. In the long term those figures may help with fine tuning a feeding schedule.


That said that would be a major pain in the arse for someone to take multiple coco ph readings over the course of an entire grow & there would be no guarantee that every row after that would have the same ph values.


Depends how closely you want to scrutinise your grow.

 

[lunarman]

Ah man, you just overthinking...
Relax and grow.

That is good advice. Won't deny that. Its good to relax as much as possible. And sometimes it needs to be said to someone.

But do you think all the guys before that came up with things like special nute schedules for autos or other tips and tricks and best practices didn't do some things seriously too? Not that this is something that compares to the good work people have done before of course.

 

[lunarman]

What type and brand coco is this - brick or loose; buffered or not; flushed/rinsed or not; etc.? Pure coco or perlite added?

Maybe, do more flushing of the coco? With nothing planted yet, can't hurt. Do a lot with tap/hose water and end with your final pHed feed pre-charge.

I would presume seeds, containing their own full nutrition for a while, are pretty tolerant of soil/water pH. Out in nature they certainly have to be pH-tolerant. Following the lead of others on AFN, I don't bother to pH tap water at 7.25 fed to seeds and small seedlings. I'm planting directly into my final Air-Pots containing 85/15 coco and perlite which has been thoroughly washed/rinsed and allowed to normalize (just let sit) for about a week before seeds are planted.

Canna coco brick with 20% perlite. I have multiple regular size pots that I have been probing. Two of them had just rinsed non PH'd and non pre-charged coco. One of them is a pot I cut in half. The other regular size. The smaller pot has way less depth of coco in it and it measure nicely pretty much top to bottom at 6.2. The other regular size pot is 6.8 at the top of the coco. And gets better to maybe 6.3 at the bottom. Then I have two more pots that were from new bricks that I hydrated with water PH'd to 5.8 and precharged with calmag, some remo kelp and 1/4 strength micro. These two pots show the same behaviour. Higher PH level near the top and lower at the bottom.

 

[lunarman]

I'm making an assumption here but every time you top feed your plant (during first few weeks of establishing in the auotpot) with feed in the range of 5.5 - 5.8ph (for most users) you are helping to adjust the coco to the correct range. That's my best guess but bottom line whatever the coco ph reading is the system works & works quite well.
It would be more interesting to know how the coco ph changes over the course of a grow at varying depths. In the long term those figures may help with fine tuning a feeding schedule.


That said that would be a major pain in the arse for someone to take multiple coco ph readings over the course of an entire grow & there would be no guarantee that every row after that would have the same ph values.


Depends how closely you want to scrutinise your grow.

Yes I don't want to get in to making a lot of effort checking PH at different levels. Just looking to see if there is a general assumption here that says the PH is higher at the top of the pot and lower at the bottom. And what if anything do I do about it.

Actually I already know what I'm going to TRY to do about it. I'm going to cut a couple more of my pots down in half today. And some of the recently made coco/perlite will go in them and I'll drop a couple of dutch passion in them.

I don't like the 16 liter 4 gallon pots TBH. My reasons are these. They are just my beliefs though. Not saying I can back any of this up with hard data TBH.

• Smaller pots will have tighter more consistent PH levels at all depths of the coco.
• Smaller pots grow plants faster plants if done right.
• Smaller plants retain less water/liquid. If possible have the least amount of saturation of the medium instead of more.
• Smaller pots are more responsive to things like flushing compared to bigger pots.
• Airdomes would have more affect on the coco above it with smaller pots. Although I'm not sure this is a good thing if its too much air.