FlytrapCare Carnivorous Plant Forums

Here's a photo of a fly trap with mineral burn. I thought this might come in handy for comparison in the future.

I was testing out some unwashed pool sand in the soil mix with this plant. I found out later that on the first wash of pure pool sand (Quikrete brand), the TDS of the water washed through was nearly 500 ppm. The second rinse actually gave me 700, but not sure if it was a false reading cause it was after the first wash. After discovering that, it confirmed my suspicions that this plant was reacting to the sand and not cool nighttime temperatures. The water from my first rinse through this pot was about 270 ppm (somewhere around there, I can't remember). I did several rinses to get it down in the 30s and I expect it will be ok now.
P.S. I added the sand Jan. 11 and this photo is from today, Feb 15 so this is after about 1 month of exposure. It didn't seem to stunt the growth as it awoke from dormancy, it just poisoned the leaves. When I did the rinse, they looked like maybe they weren't able to be triggered too as a lot of dirt, water, and perlite was moving in and out of the traps.

Yeah, that's definitely abnormal looking death. Usually it would start with the trap dying off.

Good thing you found the cause. I've never rinsed my pool filter sand, I wonder if I should start. Though I don't use the quikrete brand.

I bet how much you rinse while planting and how much rain you get plays a big factor as well.

Glad you got it back on the right track.

parker679 wrote:Yeah, that's definitely abnormal looking death. Usually it would start with the trap dying off. ... I've never rinsed my pool filter sand, I wonder if I should start. Though I don't use the quikrete brand.

I bet how much you rinse while planting and how much rain you get plays a big factor as well.

Ya, the death was accelerating towards the end. Try rinsing some of your sand by itself next time you have it out and check the TDS. Quikrete is surprisingly dirty stuff. Hopefully that's what this problem is. There's a small shred of doubt in my mind because if it's pure silica sand, what other minerals would be in it to rinse out? Is a high TDS always bad or could harmless silica dust also raise it? This pot has been indoors so it definitely didn't benefit from any rain, but I would bet one rain shower would've done the trick to get it clean.

I'll have to test it this weekend and see.

I would expect pure silica sand to be relatively inert. I found something online that said that while it's only slightly soluble it can increase TDS, but 500-700 is a bit extreme. Could be a contaminated batch....I don't know.

High TDS isn't in and of itself an issue, it's what is making up the TDS that's the problem. But as a general rule, low TDS is what you want.

I once tested the water in a tray of plants that had been growing fine for months and it was well over 100. And these were plants that are outside getting rained on. I immediately dumped the water and flushed the pots and retested. Same thing, over 100. I decided that they had been growing fine before so why sweat it. I later read that peat can increase the TDS of water. So now I just pay attention to the TDS of the water I put in and not worry about the water that's in the tray.

Makes sense!