Flushing salts from Semi-Hydro media

[splyttheprophet]

Hello all,

This is my first post on Orchid Board. I have been growing orchids for over ten years, but have only really been paying attention for the last five. Eighteen months ago, with the addition to my world of a daughter and a sudden and long overdue decision to go back to school, I found myself with very little extra time to manage my collection of sixty or so orchids. I decided to switch everything-- from bark, sphag, and mounts-- over to Semi-Hydro. Nearly everything survived, and most things flourished. I water using a pesticide sprayer with the spray nozzle removed, and it does not fill the pots fast enough to fill them to the top. It recently occurred to me that this may lead to salt buildup. This leads me to my question and the reason for my post: Is there a way, after having ignored salt buildup for over a year, to flush the pots? I have begun watering with distilled water every month or two, and the rest of the time I use tap water with a beginning TDS of about 130 ppm, to which I add one-quarter-strength fertilizer.

Thank you, and my apologies for the long-winded introduction.

[Bud]

with S/H method, you flush twice a month or every 15 days to get rid of debris, other plant wastes and fertilizer deposits...I dont know where you get salt deposits...where is the salt coming from... if you use distilled water?

[camille1585]

In order to properly flush the pots, you need to plug the two holes with your fingers, fill the pot to the brim, then uncover the holes. The water pressure is enough to clean it out. I make it a habit to properly flush each time I water.

[camille1585]

Bud- salt deposits come from regular use of fertilizer.

[zxyqu]

Camille is spot on with removing buildup of salts. I use that technique anytime there is noticeable buildup on the LECA. You don't have to do it very often if you have a low TDS water supply and don't overuse fertilizers. So maybe once every month or two just flush with water.
Also you might want to consider a different way to water so you can get water to the brim at every watering. If you don't "wash" the top LECA pellets, they'll buildup with salt quicker.

[camille1585]

The reason I flush so often is that (if I remember right) Ray noticed that the plants establish faster and grow roots faster with frequent flushing. Probably because it removes the waste products from root metabolism. But I only have 2 plants in S/H, so it's not much of a hassle for me.

[Ray]

I would like to comment that plugging the holes, filling the pot, and then letting it drain is NOT the preferred method of watering. Filling the pot rapidly while it drains is better.

Consider that in the former method, you are filling the pot with your preferred solution, and as it sits in the pot, the residues from previous waterings and plant wastes dissolve in the solution, giving you a "less than pristine" result. That, in turn, is absorbed by the medium, and fills the reservoir, resulting in that being the chemistry to which your plants are exposed. As you repeat that technique, the residual contaminant level will continue to rise.

If, on the other hand, you allow the pot to drain while you continue running your fresh solution into it, there is a much greater tendency for the residues to be forced out of the pot, leaving a closer-to-pristine environment than you would get otherwise.

I water frequently enough in the greenhouse that I don't see much buildup, but for plants in the house, I will occasionally (every couple of months, maybe) set them in the sink, turn the water on at a rate that fills the pot to the top without overflowing while it drains, and leave it that way for about 15 minutes.

Also don't forget that the most significant buildup occurs at the top of the medium where it dries, so you can dump that top layer and replace it with fresh medium as a quick, effective fix. Then put the removed medium into a solution containing about a tablespoon per gallon each of calcium nitrate and Epsom Salts, and just let it soak. The mineral residues will dissolve eventually, and the medium can be reused.

[camille1585]

Leaving water running 15 minutes is a huge waste of water. Even if it's done not very often. It may be what's best, but I can't bring myself to let all that good water disappear down the drain like that.

But when I plug the holes I'm not filling the pot with fertilized water, but clean water. After that I fill to the top with fert water and let drain. Once in a while I run water through them like you do, but no more than 30 seconds!

[Bud]

Oh I forgot you are in Europe where water is expensive. I dont pay for water in my apartment situation...the landlord pays I think $500 a month for the whole building of 78 tenants...thats how cheap water is here...so we can let the faucet drain for 5 to 10 minutes in the sink and really flush the containers. And you are right...water is cleaner in Manhattan than anywhere in the other states.

[camille1585]

I actually really don't care about the price. It could be free and it wouldn't change my behavior. The point is that water is a valuable resource, and us people in developed countries really take it for granted. And droughts are happening more and more often in Europe (and elsewhere), and we need to be careful with our natural resources! Just because we have cheap abundant water at the twist of a tap doesn't mean we need to waste it. I'm not an envirnmentalist, but do try to live my life as green as possible.