Using Physan 20

[Pilot]

Hi All--

All of my phals are in S/H and as such, their pots are pretty full of algae-- vibrant green, but something I don't much care for because I can't see the roots in action.

So I bought Physan 20. I followed the directions but it didn't do anything right off. Is it safe to assume the algae has been "hit" and will die off in the coming days?

Also, because Physan is a chemical designed to kill off things, I thoroughly drenched the pots with clean fresh water, followed by my weak fert.

After applying physan, should one flush the pot or let the physan remain? I know some of the physan will be left behind simply because the hydroton likely kept some behind but I don't want to hurt my orchids and am a bit unnerved with this stuff.

Any advice on what you do would be great-- thanks.

[ChasWG]

Interesting question. I was thinking about getting some of that to whack the algae in one of my water trays that seems to like to grow green and brown algae, gooey mess.

Also, it doesn't hurt ther roots?

[Pilot]

Originally Posted by ChasWG

Interesting question. I was thinking about getting some of that to whack the algae in one of my water trays that seems to like to grow green and brown algae, gooey mess.

Also, it doesn't hurt ther roots?

Hi Chas-- hence my question... but looking at the directions, you can spray this stuff (2tsp to a gallon solution) right on the plant to prevent or stop all sorts of fungus, rot and so on... and I know Ray sells the stuff and uses it himself as a disinfectant and to flush his pots-- but I just don't know if you leave the plants as they are of if you need to run clean water through. I ran it through so as to be cautious but we'll see.

BTW-- got your message about the garden meeting. I'll reply asap.

[King_of_orchid_growing:)]

I use Physan 20 to sanitize the pots.

I refuse to let the thing touch my orchids. Had bad experiences with it. Especially if it hits the roots.

There are algaecides available out there. Get those instead. Physan 20 isn't designed to be used against algae.

Even with the algaecides, I doubt you'll be able to get rid of them for good. As long as there's a wet environment and plenty of iron, silicates, phosphorous, and nitrogenous compounds you'll get algae.

[Pilot]

Well I've already used the physan on the pots/medium/roots so there is no turning back; however, I gave it a thorough flushing so I guess we'll see what happens.

I know people use it for just such a purpose and I don't see much difference between the active ingredients in physan versus the ingredients for other algacides. I guess I just have to be hopeful I didn't just kill my orchids!

[TylerK]

I've been using Physan for about a year now on potted, mounted and s/h orchids. It doesn't seem to hurt them at all. However, I had some live moss growing on a couple of the mounts and in one of the pots and it totally killed it off. My nice green spahg was white within a day of using it.

Tyler

[Pilot]

Originally Posted by TylerK

I've been using Physan for about a year now on potted, mounted and s/h orchids. It doesn't seem to hurt them at all. However, I had some live moss growing on a couple of the mounts and in one of the pots and it totally killed it off. My nice green spahg was white within a day of using it.

Tyler

Tyler-- how do you apply it to your s/h plants? What dosage per gallon? Do you soak the plants or just water them with physan and leave it in the pot? Or (sorry I like to be specific) do you water the pots/roots with physan and then flush the pot? Do you find it gets rid of the algae?

Its been over a day now since I applied some physan to my s/h pots/orchids and I see no change in the plants themselves and the algae, ironically, seems to be doing very well.

Thanks for your input.

[Ray]

Physan 20 is sold as an algaecide. From thier home page:
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PHYSAN 20™ is a broad range disinfectant, fungicide, virucide, and algaecide which effectively controls a wide variety of pathogens on hard surfaces and plants. Its applications include greenhouses; hard surfaces; lawn and turfgrass; seedlings and cut flowers; decorative fountains, pools and birdbaths; and plants.
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Its application in semi-hydroponics should be as an algae preventive measure, not an attempt to remove what already has grown, and a periodic drench at 1 teaspoon per gallon is adequate for that. (I usually water normally after about an hour).

If you have a substantial buildup of algae and try to kill it in place, you will end up with a dead, decaying cesspool in the pot, requiring extensive, frequent flushing to prevent issues with your plants.

If I miss a plant with preventive treatments, and it gets that bad, I repot into a clean pot and put the old one in a dishwasher.

[TylerK]

I'm certainly no expert, though I haven't seen any problems as of yet. With the semi-hydro orchids I just soak with the physan solution (as per manufacturers instructions) instead of a normal watering (no fertilizer or other additives...just water and the physan). I just fill a bucket with water, add the physan and let the plant sit in there for an hour. The remaining physan will get flushed out with the next watering. I've been doing this about once or twice a month so far.

Just as a control, I've been keeping one of my s/h orchids out of the physan solution and there is definately significant algae growth. There is very little in the pots where I've used physan, so I would say it is definately working.

I don't know if this makes any difference, but I have not been using the standard plastic pots. When I first transplant into s/h I use a large opaque plastic disposable drinking cup. Once I know that the plant is taking well to it I transfer it into a larger glass vase in which I have drilled a couple holes. I'm not sure how the glass vs plastic would affect algae growth.

Tyler

[Pilot]

Originally Posted by Ray

Physan 20 is sold as an algaecide. From thier home page:
-------------------------------------------------------------------------------------
PHYSAN 20™ is a broad range disinfectant, fungicide, virucide, and algaecide which effectively controls a wide variety of pathogens on hard surfaces and plants. Its applications include greenhouses; hard surfaces; lawn and turfgrass; seedlings and cut flowers; decorative fountains, pools and birdbaths; and plants.
-------------------------------------------------------------------------------------
Its application in semi-hydroponics should be as an algae preventive measure, not an attempt to remove what already has grown, and a periodic drench at 1 teaspoon per gallon is adequate for that. (I usually water normally after about an hour).

If you have a substantial buildup of algae and try to kill it in place, you will end up with a dead, decaying cesspool in the pot, requiring extensive, frequent flushing to prevent issues with your plants.

If I miss a plant with preventive treatments, and it gets that bad, I repot into a clean pot and put the old one in a dishwasher.

Thanks Ray-- that answers my question then about my situation. I have a pretty good layer of algae on the sides of the pots facing the window (been letting my phals grow off to the side after having seen a neat exhibit once with the phals growing as they would in nature-- so the exhibit claimed). And so I don't rotate the plants. I see no need to disturb the plants as they are still getting their feet wet in this s/h set up and doing really well. So the algae clean up will just have to wait.

My major concern was harming the roots of the plant and wasn't sure how long I could let the physan solution sit in the s/h pots with the roots in it. An hour is a pretty long time but I'm glad to hear of your practices not hurting your plants. So it is likely I didn't leave the physan long enough for anything to really work? Because I washed it out of the pot minutes later.

Ray do you also spray your plants as a preventative measure against disease/fungus etc.? In our Colorado 10% humidity air (and no, i don't use a humidity tray-- the plants seem to have adapted) I usually don't see the risk of moisture-related issues. Thats not to say a fungus or bug can't cause issue. but I haven't seen any yet.