Algae control with Physan and bleach

[terryros]

There are a variety of opinions about controlling algae growth with s/h. Physan 20 can work to treat and may be able to control growth when used on an intermittent basis. Other opinions talk about periodic use of small amounts of bleach in a flush solution for control.

I recently got an opinion that mixing Physan 20 in with fertilizer might create some substances that might not be the best for growth. I had been mixing a small amount of Physan 20 with my fertilizer solution.

Searching the forum on this topic is a little chaotic so I thought this might collect opinions in one place. Maybe there is truth out there and maybe only anecdotal opinions.

[Ray]

I have used Physan and bleach solutions, but never mixed with my fertigation solution, always as a separate drench.

[terryros]

Ray - have you mixed Physan and bleach together in a wash solution or only one at a time? I think I know the Physan concentration but am a little unclear on the bleach concentration for a wash.

[Ray]

One at a time.

Bleach at 1 ounce per gallon, Physan at no more than a teaspoon per gallon - and I'd bet you can get away with less.

[Posey]

Would you please explain to me how you do the 'drench'? I only recently started s/h growing and now how some phrag and lycaste pots that have serious algae growth. I haven't done anything about it cause I don't have a clue how to go about it (even though I have some physan). Maybe I've let them go to long and I'll have to start with freash media before its all gunked up?

Generally speaking however, if the pots aren't too gunked up and you were doing yours :

Do you tilt the pot to get out residual liquid and then run buches of dilute physan through it or what? Do you leave it in there? If so, how long? Do you have to flush it out well with water afterwords? Should you generally do this periodically as a preventative measure even when you don't see algae growth? If so, how often? Any details I missed? Any s/h potted genus or species that tends to be negatively impacted by this type of treatment?

Lastly, is it OK to use the pool algacide stuff instead of the physan for this?

Sorry, I know, that's alotsa questions.

Thanks for your consideration.

[Becca]

To add to Posey's questions....does the algae really hurt the orchids?

[samizook]

Originally Posted by Posey

Would you please explain to me how you do the 'drench'? I only recently started s/h growing and now how some phrag and lycaste pots that have serious algae growth. I haven't done anything about it cause I don't have a clue how to go about it (even though I have some physan). Maybe I've let them go to long and I'll have to start with freash media before its all gunked up?

Generally speaking however, if the pots aren't too gunked up and you were doing yours :

Do you tilt the pot to get out residual liquid and then run buches of dilute physan through it or what? Do you leave it in there? If so, how long? Do you have to flush it out well with water afterwords? Should you generally do this periodically as a preventative measure even when you don't see algae growth? If so, how often? Any details I missed? Any s/h potted genus or species that tends to be negatively impacted by this type of treatment?

Lastly, is it OK to use the pool algacide stuff instead of the physan for this?

Sorry, I know, that's alotsa questions.

Thanks for your consideration.

I too, would like to know everyones techniques.

[Posey]

Originally Posted by Becca

To add to Posey's questions....does the algae really hurt the orchids?

I wasn't really THAT worried about it til it started to look like it might be blocking the air spaces!!! Pretty bad eh??? LOL. It hasn't hurt anything with mine YET though, if that helps!.

[terryros]

While waiting for some who must know more I will say that I had some modest algae growth beginning in some s/h pots with LECA (Catt, Phrag, and Phals). I started adding about 1/8 teaspoon per gallon of Physan 20 to the fertilizer solution that I use to water and keep the solution level at about 1 inch. The algae growth has regressed. My concern is whether the constant exposure to the Physan might cause longer term damage to roots/plants and whether the Physan might be interacting with the fertilizer to cause a bad reaction. We just might not know the answer. Ray seems to want to keep the Physan or bleach as an independent, periodic treatment rather than as a constant.

[Ray]

When I say "drench", I mean water it the way semi-hydroponics is supposed to be watered - fill rapidly to the top and let it drain - but using the disinfectant rather than fertilizer.

No matter what you use, the treatments are meant to be preventive, not curative. Nothing will remove the algae that is present. At best, when treating an already-algaefied pot, you will kill it, which could lead to some pretty bad conditions in the pot as it decomposes. The best thing to do is to repot into a clean pot and keep up with the preventive treatments.

Keep in mind that the algae is only growing where light, water, and nutrition come together, so the interior of the pot is untouched.

Unless the top surface or drainage holes become clogged, this is nothing more than an aesthetic issue.