New Primeagra question/problem
 

Well, I've tried the new primeagra, and it has a unique tendency to build up a pretty thick salt crust on the top. The old primeagra didn't do this at all. I flush the pots every watering, and I'm still using tap water and 125 ppm N MSU.

Anyone have any experience with this? It's unsightly at best, and I don't want to be damaging the plants with it.

I suspect it may have something to do with the tap water. As an experiment why not flush with distilled water (available at grocery markets) for a while and see if it goes away? Mine doesn't do that and I am using RO water with MSU.

I agree that tap water is a potential culprit, but that still doesn't explain why it happens with new primeagra but not the old.

I have no clue. Was just making a guess.

I'm having the same problem. Plus almost all have snow mold, yuck! However, I noticed that the plants I repotted first, went though a period of crystal build up, they were 2-3 weeks ahead of the other, and now it's not so bad. Maybe the new stuff just needs a good leaching. The most recently repotted plants are doing the crystal build-up now. That's my thought on it. And BTW I use well water that is softened with potassium pellets. And I did do a straight watering session with RO water and I think it helped with the original repotted plants, I'll be doing that with the rest of them this week.

tindo, it's crystalline, and dissolves again briefly when I water, but later that day returns. I'll take a picture today.

I've been playing with the stuff for about 18 months at this point, and I think there are two factors in play.

I suspect it's primarily due to the fact that the new stuff wicks better than the old stuff.

Remember that the majority of the evaporation is from the top, and that the medium wicks nutrient solution - with all of the dissolved solids in it - up to replenish what's lost (nature hates a gradient). If the wicking is better, the mineral transport is, too.

I have not seen such an issue in the nice, humid greenhouse, but have seen it when bringing blooming plants into my much-drier house.

Secondly, I believe the smooth, microporous surface of the new stuff simply shows the precipitate better. With the old version, all of the little nooks and crannies in the surface could be loaded with minerals, but you couldn't really tell. With the relatively smooth surface, it's more prominent.

FWIW, another difference seems to be that the deposits on the new stuff are easier to redissolve, suggesting they are actually less buildup. I have seen used, old PrimeAgra particles, after soaking and drying, still have plenty of buildup on them, while this stuff washes away readily, as rsfrid mentioned.

I guess the bottom line is that it might not be the problem we think it is.

I also have noticed a salt deposit (a whitish fine crystalline coating on top of the new PrimeAgra), although I have never used the older PrimeAgra so I have no comparison.

It seems to me that the deposit is from the PrimeAgra itself, because it exists in the container of a carnivorous plant I repotted into PrimeAgra as an experiment. Carnivorous plants are not fertilized (except for mild foliar feeding in some cases, but not in the case of the plant I mention here), and I have watered only with pure collected rainwater. Yet despite the pure water, the deposit persisted for a while. As a note, the salts were enough to burn the leaf tips and margins of the Cape Sundew (Drosera capensis) that I planted in it, but I hasten to add that carnivorous plants are unusually sensitive as a rule to dissolved minerals (TDS, or total dissolved solids) in the water or their medium. Now however, several weeks later, most of those salts have leached out and the crystalline deposits appear greatly decreased, although still present to some extent.

It would therefore seem that there may be some water soluble minerals in the new PrimeAgra from the manufacturing process.

However, a little extra leaching or soaking and rinsing at first should compensate and get rid of the excess, right?
:)

Additional note, added later--
After writing the above, I began an experiment. I washed and rinsed enough of the new PrimeAgra to fill two 16-ounce plastic cups, one with the fine-grade and one with the standard coarser grade of PrimeAgra. The water was pure collected rainwater. Then after filling the plastic cups, both undrained, with the PrimeAgra, I added rainwater to within an inch and a half of the top of the cups. After sitting overnight, and then in the sun today, there is clearly a crystalline deposit on the top surface of both the fine and coarse grade of PrimeAgra. I plan to let the water evaporate completely from both cups and then observe and photograph the result. I'll post a photo or two here at orchidboard.

To try to get rid of most of whatever minerals are causing these deposits, I plan to soak, drain and rinse the PrimeAgra I use in the future, perhaps more than once. My orchids don't seem to be much affected, if at all, by these minerals, but the Cape Sundew was pretty obviously affected. I wonder whether there is much sodium in the mineral deposit, because sodium is a very active flux in clay and in glaze mixtures and I'm wondering if any was used in the manufacturing process for PrimeAgra. If so, or just to be on the safe side, I plan to remove as much as I can before placing a plant in the medium.

All that said, so far I do like PrimeAgra and hope to learn how to use it to best advantage for my plants and for myself.
:)

Edit, added Feb. 5, 2007
The results of the test I mentioned above, with a photo, can now be seen a little later in this discussion thread.
:)