What's new
TerraForums Venus Flytrap, Nepenthes, Drosera and more talk

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

HighTDS levels

After seeing some 'burning' on a few leaves I thought I'd test the TDS levels of the water and make sure that there were no organics. Turns out the levels in the water were above 100 ppm and after test flushing some pots, one pot ended up being around 650 ppm.

I discarded the soil, repotted (peat and sand) what I wanted to keep and cleaned the tray out. I have Drosera, Byblis, Stylidium, and Sarrs seeds/seedlings sitting in the tray. This seems to be a re-occuring cycle and I'd really like to stop it! None of the soil had the 'egg smell' this time from cyano-bacteria which I use to get as well. I let the tray dry before adding more water. Does anyone have experience with this issue? Where are these TDS coming from?!

The only additives I've used is neem oil. Does it eventually break down into organic compounds? Would adding a sulfur based fungicide to the water help keep the organics off the soil due to the H+ ions bonding or would the organics hold there place in the soil?

Just some thoughts, any help is VERY appreciated, thanks for reading.
 
I didn't see you mention the obvious - what's the TDS of the components of your media mix? Even though my sand is close to 100% quartz, I find that I must wash it before use as the dust (& whatever) on it provide high TDS readings if I don't. A friend also washes his peat before use due to high TDS... I've found similar issues with APS & perlite.
 
I've tested each individual component individually before mixing and the TDS meter reads 0ppm for the sand and usually around 10 ppm for the sphagnum peat moss. The pots that do have perlite have been in use for no more than 2-3 months tops so I seriously doubt that it is due to it breaking down as from what I've read usally takes 1-2 years.
I suppose washing would help get rid of the extra ppm in the peat but at 10 ppm I really have never had any issues with it. The outdoor pots do not have this problem and I've also never treated them with neem.
Does anyone have any sort of info as to if and how quick neem breaks down?
I've also tested the ppm of the neem I'm using in the diluted concentration and the meter is blind to it. My water is also at 0 ppm.


Edit: Looking at the neem composition percentage wise, it looks like all of the components have hydroxyl groups and nothing in terms of N-P-K. Seems that I'm blaming the wrong thing...
 
Test your water ???
 
I agree that it sounds more like an issue with your water than with your media. What is its source and do you regularly test it? Mine seldom rises above 10 ppm and is generally lower.

Also, I have never washed media before using it -- ever . . .
 
I had mine checked, and it's in the 60's. Good for most, all except Sphagnum and the really picky. By the time anything builds up, the rains come and flush it out.

We were having fun checking other water around. Janet's water read in the 200's, and the bottled water? Don't ask! My bottled water was a different brand, and we got NO reading at all!
 
Thanks for the help everyone;

I do regular checks on my water as I use a RO/DI system. I purchased it about 2-3 months ago and only get about 6 gallons a week out of it so I do not think my filters would need replacement yet.
On another note, my Nepenthes do not have this issue and are growing just fine. The TDS meter reads 0ppm as of yesterday for a fresh batch of RO/DI water.

I want to point the finger at the medium since one pots had ppm values of 600+ while some were around 100+. I've never added fertilizer of used hard water so how the values were raised so high is a real head scratcher. There will occasionally be algae in the tray indicating that there is some nutrients in the tray. It's also not the first time that I've had these levels occurs, meaning something must be STILL in the tray or I am still doing/using something that cause these high levels.
 
Perhaps it's the sand. Do you flush it well before using it? What kind is it?
 
Hi Tony, thanks for your input.

I did check the water flushing from the sand. I picked up a 50 lbs bag of pool filter sand. The granules are a bit larger than silica sand granules but the flushed water tested at 0ppm.
Tonight I will snap some pictures of all the media separately and get some readings to post on here.
 
  • #10
Temperature affects TDS reading. And when was the last time you calibrated your meter?
 
  • #11
The meter was last calibrated when I sent it back in (a little less than a year ago).
I've tried testing other sources of water to make sure that readings were correct. I get ~250 ppm for tap water and 0 ppm for my RO/DI system which seems right since the DI filters are suppose to get the last of the minute particles.
 
  • #12
i guess i should first say that TDS are not organics in the water, it's exactly what it means: total dissolved solids - anything that's dissolved in the water, mainly salts, carbonates, things like that. organic compounds are not water-soluble and don't contribute to TDS. Also, the rotten egg smell you mention is due to the production of sulfides which happens under reducing condtions, i.e. no oxygen. if you are getting that smell, you are keeping your soil far too waterlogged and stagnant.

i'm a little unclear as to what exactly you're testing. do you have pots sitting in a tray and you're are testing the water in the tray? when you say a test flush - are you running water through a pot, collecting it as it drips out the bottom and checking the TDS of that?
 
  • #13
Silica pool sand is about as good as you can get...

I would try testing your peat as Sarracenia mentions, collect the water that comes out the bottom and see what reading you get. Perhaps you have a bad bag of sphagnum peat?
 
  • #14
Sarracenia you correct about the sulfides and smell relation. This use to be an issue which I have since resolved by letting the tray dry out in between waterings.

I have a large black tray which I sit the pots in, all the water is shared between these pots. I tested this water and obtained a reading ~130ppm. I pulled every pot did the flush technique by pouring about 4-5 measuring cups of water on the top of the pot and collecting it as it exited the pot through the bottom. This is where I was obtaining my readings from. This is also where I obtained a reading of ~600+ ppm from one of the pots.
I was assuming that I had organics (Nitrogen, Potassium etc...) in the water mainly because of the 'burnt' look on some of the leaves on my plants.
Since the meter is reading high though it sounds like I have salts in the water, otherwise the meter would not have read anything...correct?

I'll post some pictures tonight of the test batches, hopefully it's something i'm CLEARLY missing that's right under my nose. Thank you all again for your help.
 
  • #15
Sarracenia you correct about the sulfides and smell relation. This use to be an issue which I have since resolved by letting the tray dry out in between waterings.

I have a large black tray which I sit the pots in, all the water is shared between these pots. I tested this water and obtained a reading ~130ppm. I pulled every pot did the flush technique by pouring about 4-5 measuring cups of water on the top of the pot and collecting it as it exited the pot through the bottom. This is where I was obtaining my readings from. This is also where I obtained a reading of ~600+ ppm from one of the pots.

If I flush any of my pots and collect that resulting filtrate, I too would be getting readings like you have experienced -- simply from the harmless, fine particulate matter in some of my mixes. TDS can either by innocuous or a real problem -- depending upon just which total dissolved solids are in suspension (peat particles, etc. in solution would raise the meter conductivity as would truly harmful salts) . . .
 
  • #16
I could be mistaken, but if you have something like a portable TDS meter, I think those actually measure electrical conductivity, which is used to estimate TDS...i.e. the more dissolved, charged particles in the water, the better it will conduct electricity; like if you have table salt, it dissolves to Na+ ions and Cl- ions. I am going to assume your soil mix has sphagnum in it, which as we know releases acids, which also dissociate into positive and negatively charged ions in water, so it would make sense to me that deionized water that passes through it would contain these acids, which would give you measurable quantities on a conductivity/TDS meter. So I guess what I'm saying is that getting readings on your TDS meter in your tray water may not necessarily be a bad thing. As far as if the numbers you get are what would be expected from the spagnum, I can't tell you. I do work in a water quality lab and we measure conductivity in the field sometimes. My boss is gonna be gone on Wednesday, so if I remember, I'll stick some live sphagnum in some RO water tonight, and if I have time, i'll measure the conductivity on Wednesday.

Sarracenia you correct about the sulfides and smell relation. This use to be an issue which I have since resolved by letting the tray dry out in between waterings.

I have a large black tray which I sit the pots in, all the water is shared between these pots. I tested this water and obtained a reading ~130ppm. I pulled every pot did the flush technique by pouring about 4-5 measuring cups of water on the top of the pot and collecting it as it exited the pot through the bottom. This is where I was obtaining my readings from. This is also where I obtained a reading of ~600+ ppm from one of the pots.
I was assuming that I had organics (Nitrogen, Potassium etc...) in the water mainly because of the 'burnt' look on some of the leaves on my plants.
Since the meter is reading high though it sounds like I have salts in the water, otherwise the meter would not have read anything...correct?

I'll post some pictures tonight of the test batches, hopefully it's something i'm CLEARLY missing that's right under my nose. Thank you all again for your help.
 
  • #17
Yes, my TDS does in fact measure total disolved solids using electrical conductivity. Are these not reliable? It seems to have given me pretty accurate readings (so I thought) with water tests.

As I said earlier today here are some pictures for clarification. The mediums were taken straight out of the bag and NOT rinsed, just mixed with the RO/DI water.

The TDS meter itself
IMG_2758.JPG


TDS meter testing my RO/DI water, fresh batch from this morning
IMG_2759.JPG


TDS meter in sand and water mixture. I poured the sand then the water and stirred then let sit for about 15 seconds. (Equal proportions)
IMG_2760.JPG


TDS meter in peat and water mixture. I poured the water on the peat and worked the mix together until the peat was saturated (hard to eyeball equal proportions with this but tried to)
IMG_2761.JPG


The tray method which I am/have been using
IMG_2762.JPG


TDS level in water sitting in tray after clearing out bad pots and flushing the pots which I kept.
IMG_2763.JPG





Overall it seems that the only source of TDS is the peat, but I did not think these levels (36 ppm) would be anywhere too high. I also cannot understand how 36 ppm could add up to 64 ppm. The concentrations in the tray water should not vary from those in the pots...right?
 
  • #18
Those meters are very dependable and there is nothing wrong whatsoever with the algorithm to establish TDS / ppm. You're always going to get some "higher" reading resulting from any filtrate from your pots; simply flush them with low-TDS water and don't worry about it. If you remain concerned about your meter's accuracy, get some calibration solution (usually 250 ppm saline) and test it yourself.

Most TDS meters nowadays also correct for temperature differences.

I grew these plants for years without ever considering TDS / ppm, and far more is being made of this issue than is really necessary; simply ensure that your water is about 50 ppm or below, and all will be well . . .
 
  • #19
Thanks a lot for the feedback BB, how often do you recommend flushing the pots? Once every 4 weeks? more often?
 
  • #20
Thanks a lot for the feedback BB, how often do you recommend flushing the pots? Once every 4 weeks? more often?

You're welcome . . .

If you're truly concerned about the pots, flush them out every couple of weeks (opposite the time, when or if, you fertilize) or whenever you like. Most of my pots have live sphagnum in them (at least as a top dressing) and that serves as a great indicator for any possible mineral, algal, or fertilizer accumulation . . .
 
Back
Top