umm... sorry dummie q. what is TDS?
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This is a discussion on TDS. question within the General Orchid Culture forums, part of the Orchid Culture category; What is the acceptable TDS. for general use , not for Paphs. Phrags. Massies and ...
What is the acceptable TDS. for general use , not for Paphs. Phrags. Massies and other sensitive orchids .
Most of what I have read pertains to Semi. Hydro . not ones in bark , Spag. ect . A friend and I have been having a running conversation regarding this . Also is there any way to reduce the TDS. other than adding Ro. or rain . Your feed back is appreciated . Gin
umm... sorry dummie q. what is TDS?
Total Dissolved Solids.
To improve the water use a water filter.I used 1 & it lowered my tapwater from about 280 pmm to about 140 ppm.
As for an acceptable level for general orchids .
Most of mine are given the same fert/water as my paphs/phrags & they seem to flourish.I DO treat some differently(mainly Cymbidiums & my Ascocenda).
I found an old post on this forum asking the same thing , it says 60 to 120 is acceptable , what kind of filter are you using ? what is in it charcoal ?
My friend grows indoors about 150 plants has an Ro. unit it creates a lot of work filling a barrel with the Ro. Her Tds. is very high .
I can use 2 Gal.tap and 28 Gal Ro. or rain . Tds. 29 Ph. 6.6 to 6.8 . Run off from first watering is ... Bark Tds. 44 Ph.6.6... Spag. Tds. 51 - 52 Ph. 6.2 ... Pellets not s/h .. Tds. 48 Ph. 6 to 6.6 ... Aussie Gold Tds. 70 Ph. 6.8 to 7 ... Pro Mix Tds. 91 Ph. 6.2 before flush after flush Tds. 55 Ph. 6.2 . Thanks for the replies Gin
Hmmmmm .... I've had that weird Catt bloom, and I use.....
Southern California Tap Water!!!
Think there could be a link??? Maybe that's why I kill all the dends I get.
I collect rainwater in 2 large containers , these are connected to the downpipe from my gutters.They hold roughly 350 litres(80 gallons).My roofing material is concrete tiles so fairly inert.TDS is 7 & PH is roughly 7.
The water filter i use is a Britta filter , probably called something else your side of the pond.
My rainwater is very sensitive to any additives , PH will move up or down massively when adding fertilisers.Buffering it with 10% tapwater does help to minimise the swing in PH but i don,t add any tapwater.
The fert solution i use which is made up off a nursery fert specially for rainwater + calcified seaweed suspension + a natural fert gives me a PH of about 6.8 & a TDS of about 200.Of this roughly 100 PPM is nitrogen.
I do use a calibrated Ph meter but the TDS meter is difficult to calibrate .
This mix(Ph6.8 + 200PPM) i use for Paphs.For the other plants i add a little lemon juice to take the Ph to 5.5 to 6.
Bark mixes tend to have a significant buffering effect on the water used , where as LECA(clay pellets) does not effect the Ph as much.
Adding a little calcium to the mix(as a top dressing) for paphs will also help to keep the Ph up , as quite a number of the paphs seem to like the Ph around to above 7.
For the heavier feeders i add some Osmocote(slow release pellets) as a top dressing & fertilise them more often.
This is still an ongoing experiment to see what works but having a mixed collection some plants obviously will have to make do with less than optimum levels.
Here is some information from William Cullina's book, Understanding Orchids that I posted a review on some time ago.
"The TDS reading is the sum of all the ions floating around in your sample, and it is the ions - especially sodium and potassium - that stay behind as salts in the mix and the roots after the water evaporates. Thus the higher the TDS, the poorer your water is for orchids. The reading is given as a percentage, expressed as parts per million (ppm) or the equivalent mg/l, of dissolved salts in a given volume of water.
Rainwater collected from a roof has an average TDS of 10-20 ppm. If your water tests below 60 ppm, then it should be fine for your orchids. A TDS of 60-120 ppm is a bit high, but if the sodium tests below 10 ppm the water quality should be all right. You probably should repot more frequently, and it is important to flush the pots thoroughly at every watering. Also avoid heavy doses of fertilizer to keep the ppm of nitrogen below 100. Water with a TDS of over 120 ppm is really unsuitable for orchids, especially if the sodium is above 10 ppm. Even at a TDS of 150 ppm, the water probably won't taste salty to you. To give you some perspective, drinking water is considered "safe" with a TDS lower than 500 ppm. Swimming pool water may have a TDS of 1000-2000 ppm, mostly from the chlorine, and seawater weighs in with a whopping average TDS of 34,200 ppm! So you can see, it doesn't take much salt to make water too salty for orchids."
I called my local municipality last year and although I don't remember the exact number, I think my tap water rang in around 235!
However, I water all my plants in the winter (and sometimes other times of the year if I don't have rainwater) with 'spring water' that I get from a tapped spring about 1 mile from my place. I've never tested it but I've been told it has "a lot" of "trace minerals" in it as you would expect; I've never had any problems with this (that I'm aware of!) (This is also my only source of drinking and cooking water...is is deeeeee-licious!)
You can buy an EC meter (electrical conductivity) to get a fairly accurate reading of the TDS in your water samples. They usually cost less than $100.
Hope this helps.
Thanks Matt I copied your post , and will send it to Maggie , I also use rain or Ro. with a little tap added to it . For the heck of it I tested my straight tap . Ugggh ! Thanks again for the info . Gin