Need recommendations for LECA

[Bef]

You might try to reduce your fertilzer to 50 ppm. This is the concentration that Ray is now using (instead of 125 ppm).

I also switched from 125 ppm to 50 ppm and it probably helped to reduce mineral buildup.

BTW, can you let me know what device you're using to get the TDS from your water?

[DTEguy]

Originally Posted by Bef

You might try to reduce your fertilzer to 50 ppm. This is the concentration that Ray is now using (instead of 125 ppm).

I also switched from 125 ppm to 50 ppm and it probably helped to reduce mineral buildup.

BTW, can you let me know what device you're using to get the TDS from your water?

Hi Bef,

Yeah, I thought about that too. I recently bought a cheap meter at amazon, you can find it in this link:

Amazon.com: HM Digital TDS-EZ TDS Water Quality Tester with Auto-off Function TDS-EZ: Home Improvement

I am not sure about it's accuracy, but it seems to be very consistent.

[Ray]

All brands of LECA are loaded with dissolvable solids when they are manufactured. It is a remnant of the binders, processing aids, and water used to quench them.

ALL mineral deposits occur upon evaporation of the solvent - water, in this case. If the wicking rate outstrips the evaporation rate, and you flush sufficiently, there is no buildup to be concerned about. If evaporation wins, it wins at the top of the medium in stuff that wicks well, and lower in the pot for those that don't.

Yes, a better wicking LECA provides more surface area for evaporation, but it also provides a better environment for the plants. If you're trying to reduce wicking as a way to reduce buildup, I suggest that semi-hydro culture is not for you.

[DTEguy]

Originally Posted by Ray

All brands of LECA are loaded with dissolvable solids when they are manufactured. It is a remnant of the binders, processing aids, and water used to quench them.

ALL mineral deposits occur upon evaporation of the solvent - water, in this case. If the wicking rate outstrips the evaporation rate, and you flush sufficiently, there is no buildup to be concerned about. If evaporation wins, it wins at the top of the medium in stuff that wicks well, and lower in the pot for those that don't.

Yes, a better wicking LECA provides more surface area for evaporation, but it also provides a better environment for the plants. If you're trying to reduce wicking as a way to reduce buildup, I suggest that semi-hydro culture is not for you.

Yes, I am trying to figure out if S/H is the right system for me.

I was wondering if you can share with us if you checked the TDS of primeagra after you clean them? Do feel that the material is inert and doesn't have high ionic binding capacity?

Thanks!

[Ray]

I once took some thoroughly cleaned material - done by soaking in RO water for a week, changed daily - and sealed it in a jar of RO for over a year, and saw no shift in the pH or TDS. By soaking in water containing any dissolved minerals, include the calcium nitrate and/or magnesium sulfate, you are not totally stripping the surfaces clean, but are merely replacing the unwanted residues with desirable mineral ions.

LECAs in general have very few ion exchange sites, as the exposed crystal lattices tend to be vitrified to a significant degree, so "taken out of the equation", if you will. It is those sites (along with organic matter) that provide the majority of CEC in soils.

[DTEguy]

Originally Posted by Ray

I once took some thoroughly cleaned material - done by soaking in RO water for a week, changed daily - and sealed it in a jar of RO for over a year, and saw no shift in the pH or TDS. By soaking in water containing any dissolved minerals, include the calcium nitrate and/or magnesium sulfate, you are not totally stripping the surfaces clean, but are merely replacing the unwanted residues with desirable mineral ions.

Yes, the cationic exchange is merely replacement; and magnesium's high solubility in water makes it easier to be taken out later. That's a really good study which proves that there is virtually no ions leeching from the material.

Originally Posted by Ray

LECAs in general have very few ion exchange sites, as the exposed crystal lattices tend to be vitrified to a significant degree, so "taken out of the equation", if you will. It is those sites (along with organic matter) that provide the majority of CEC in soils.

I didn't expect the CEC to be completely zero but it is good to know from you that it is low. Thanks again for the input.

[DTEguy]

Switched to hydrotons....so far so good. Haven't seen any salt deposits and roots are taking it very well.

[Discus]

The "cleaner" the water you rinse with, the less build up you will get; you may find (it may be a worthwhile experiment) that your tapwater alone has enough dissolved minerals to cause problems, so flushing with that will not help - rainwater, RO or distilled, however, should properly "flush" excess minerals away.

I don't actually do semi hydro, but I do grow some plants in LECA (hydroton brand), and I sometimes see some buildup on them; flushing with RO gets rid of it pretty fast.

[RosieC]

I agree with Discus,

I used to flush with tap water and saw build up of deposites, I now flush only with rain water and it seems to keep the build up levels down/build up is slower.

[DTEguy]

Thanks for the input, I will remember to do that once in a while.