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TDS meter or test strips

Posted: Sun Jan 10, 2021 8:59 pm
by Panman
On a wild hair, I got out some old aquarium test strip to test my water. The TDS reading was about the same that I see on my meter. What was interesting to me was the carbonate reading. My TDS is pretty high, it is 72, but the carbonate reading, which I think is closely tied to calcium, is pretty low. What do think of the benefit of test strips over a meter?
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Re: TDS meter or test strips

Posted: Mon Jan 11, 2021 5:09 pm
by Matt
Interesting. I am not familiar with these test strips but yes, I think they could be more informative than a standard TDS reading. I think that the minerals most CPs are sensitive to are calcium and magnesium. Though, I have only read that and seen it posted around the web at various places. I've never seen any sort of scientific study done to prove this. However, I have seen plenty of photos of plants killed by using tap water in the midwest where the mineral content is high coming from ground water (well water). And most of the geology of the midwest US is limestone, which is composed of calcium carbonate and is very soft, leeching calcium into the water.

Perhaps you could do some sort of experiment?

Re: TDS meter or test strips

Posted: Sun Jan 17, 2021 4:29 am
by Supercazzola
I have a very hard time in my other hobbies when folks use test equipment that actually require other (better calibrated) test equipment to check to make sure the cheaper ones are working. Not suggesting that to be the case with your strips or your TDS meter.

Honestly, I use my 15 dollar TDS meter from china as just that, a $15 Chinese tool. If I really want good readings, I’d invest in a lab quality one. That being said, all I care about is understanding if something changes. So where my 19 ppm is actually 19 or 10 or 30, isn’t important as long as it keeps showing 19. If it jumps to 25 all of a sudden, I have to worry.

Same with my touch less head thermometer. It consistently shows me about 3 degrees cooler than I actually am, but it does it consistently. When I did have a fever, it reflected a change / increase, but again, it was about 3 degrees too low.

Re: TDS meter or test strips

Posted: Sun Jan 17, 2021 4:52 pm
by Panman
I agree with everything you have to say. My question was if it would be better to be measuring carbonate hardness versus general hardness. Back in the day before we had or could afford TDS meters, CP growers were all about the Ph of the water. That is why I am thinking that carbonate hardness might be a better measure of water suitability than TDS.

Re: TDS meter or test strips

Posted: Mon May 15, 2023 2:52 pm
by Intheswamp
I woke up this morning and started running rabbit trails for some reason...done got all scratched up with briars and everything...mosquito bites, ticks crawling, and probably have chiggers camping in my drawers by in the morning. So, I thought I'd stick my briar-studded nose into this old stump hole and see what runs out. And remember, I'm "OCD-Me"! :lol:

Anyhow, I've been mulling over the idea of investigating the water and grow mixes that I'm using. My rain water is usually less than 5ppm, and most of the time between 1-2 ppm if I let the roof rinse well before catching or if it rains for an extended period of time. Most of the drain water from my pots shows their TDS to be between 50-75ppm. But, it seems that nearly all of my young seedlings struggle after germination...sarrs, sundews, and flytraps. Leaf-cuttings seem to do well. Most seed germination is done with a peat moss based mix whereas most of my leaf-cuttings are started on live sphagnum or a mix of live and dried sphagnum. That may be a big part of the difference right there. I dunno, the biggest problem I have is probably between my ears. ;) :lol:

But, I'm thinking of getting something to test little deeper into my cultivation practices. The chinese-built pH meters look nice and handy, basically identical-looking to TDS meters of the same origin. I've seen reviews from "great" to "terrible". In the past I've seen where pH meters need to have their probes "wet" all the time and maintenance is required or they get out of kilter fast. :| I'm not a really organized person nor do I wash my car weekly, so paying close attention to a pH meter might not be for me...though I do shake off and dry my TDS meter off with my T-shirt if that counts for something. :mrgreen:

Test strips seem like they would be more up my alley...rabbit trail...whatever. They come in matchbook form or in sealed plastic containers. I think I'd prefer the plastic container for longevity/storage purposes.

I referenced the cheap pH meters up above but after reading Panman's comments about carbonate levels and doing some reading down that trail I'm beginning to think that the carbonate testing might be the route to take.

Over the last couple of years what have ya'll come to a conclusion on (and I know there will be different conclusions) other than measuring TDS what tests are good for water and grow mixes?

Re: TDS meter or test strips

Posted: Mon May 15, 2023 2:59 pm
by Panman
I would avoid all but the most expensive meters. Like you said, most of them are junk and a bad reading can cause you a world of hurt. As far as TDS meters go, I use one but regularly check it against known water to make sure that it isn't very far off. Water test strips that you use for an aquarium are very reliable. You can go really deep into it and get the chemical test kits. For testing soil, a test of the water that is filtered through it isn't very accurate. If you are trying to measure a change, then using the same amount of media and water for each test will give you a general understanding of how it is changing. For actual testing of minerals and PH level, I would probably stick with test kits that are designed for testing soil. You can find these at garden centers. They test a specific amount of soil and use distilled water to give accurate readings. Test strips and test kits can get pricey, so doing regular tests that way can certainly impact your wallet.

Re: TDS meter or test strips

Posted: Mon May 15, 2023 3:10 pm
by davinstewart
Please also bear in mind that TDS meters are sensitive to temperature so please make sure your samples are at room temp before measuring.

Re: TDS meter or test strips

Posted: Mon May 15, 2023 3:14 pm
by Intheswamp
Thanks, Panman. I've got an old soil test kit. I was concerned with the reagents in it getting old, but as of probably three years ago I sent a soil sample from my garden to Auburn and the results from there and what I showed with my test kit were definitely "close enough for government work"...which, in afterthought, might not be so good. :lol: I'll probably tinker with it for a while and see what I can figure out. As the saying goes, "It's paid for". ;)

Re: TDS meter or test strips

Posted: Mon May 15, 2023 3:19 pm
by Intheswamp
davinstewart wrote: Mon May 15, 2023 3:10 pm Please also bear in mind that TDS meters are sensitive to temperature so please make sure your samples are at room temp before measuring.
Wellllll.... Most of the meters state something about temperature calibration. I think the sellers want you to *think* they are auto-calibrating or maybe they really are. This level of meter is definitely not going to be aboard the International Space Station, though. ;)

You might want to check out this post that I made a while back. At the TDS levels that we're working I don't think temperature is really a big issue:
TEMPERATURE AND TDS MEASUREMENTS

Re: TDS meter or test strips

Posted: Wed May 17, 2023 2:41 pm
by Intheswamp
From what I've found it appears that the recommended pH range for most CPs is 4.5-4.5. If this is the case would a pH test that measures as low as 4.0 be good enough?

Re: TDS meter or test strips

Posted: Wed May 17, 2023 2:58 pm
by optique
Does the PH even effect the plants? I know lower PH keeps the media microbe resistant. My tap water is 7.2+ and as long as i keep the media fresh i have never had a issue.

Re: TDS meter or test strips

Posted: Wed May 17, 2023 4:06 pm
by Intheswamp
optique wrote: Wed May 17, 2023 2:58 pm Does the PH even effect the plants? I know lower PH keeps the media microbe resistant. My tap water is 7.2+ and as long as i keep the media fresh i have never had a issue.
Hmm, I would think pH would affect the plants...it affects about everything else. :?:

Re: TDS meter or test strips

Posted: Wed May 17, 2023 4:46 pm
by optique
I really was asking a question. I know most plants prefer a PH because it can effect nutrient intake. Like tomatoes seem to like 6.5-6.8 but would that effect CP's?

Re: TDS meter or test strips

Posted: Wed May 17, 2023 6:02 pm
by Panman
If you are growing in peat or sphagnum, those media are naturally acidic and will reduce the PH of the water you are using. Carnivorous plants prefer an acidic soil, presumably that they are designed to not require a lot of nutrients. Similar to adding fertilizer, raising the PH of the soil will make more nutrients available which could be damaging for the plants. Mexican pings excepted, of course.

Re: TDS meter or test strips

Posted: Thu May 18, 2023 1:41 am
by Intheswamp
optique wrote: Wed May 17, 2023 4:46 pm I really was asking a question. I know most plants prefer a PH because it can effect nutrient intake. Like tomatoes seem to like 6.5-6.8 but would that effect CP's?
But, most plants prefer *the correct* pH for them, it enables the plant to uptake more nutriets...cation exchange (which I know just enough about to be dangerous!<g>). Most of my experience with pH and plants has been with vegetables. Sure, most plants can tolerate variations in one direction or the other but there are sweet spots that they produce the best at. ;) I would think that CPs in a 6.5-6.8 pH would not do as well as they would in a 5.5 or even lower pH.

I'm just curious about things, I guess. The "OCD-Me"....in me. :mrgreen:

For instance, if someone relies exclusively on distilled water, which appears to basically have a neutral pH in most cases, could that over time raise the pH of peat-based grow mix? The peat moss is so strongly acidic I'm not sure the relative neutralness of the distilled would have an effect over time or not. With rain water, most of the time it is acidic. It seems that that is the "natural" water that the plants get in the wild so constant use of it should be fine, again...I guess. :?

I like to tinker around with things, but I'm no scientist, thus my questions on what I need to get an idea of what I'm doing with my plants. I know that you do quiet well with your plants so don't change anything because of my antics. ;) Your water source is great and apparently your climate is, too. Down here we have 350ppm out of the tap and an ugly climate at times with the heat...my main water source is rainwater and thankfully I have a metal roof to work with. I dread the drought we will inevitably have this summer. But, I'm going down a rabbit trail with that.... :mrgreen: