No.

To the best of my knowledge, no Physan or SA 20 shouldn't affect the fertilizer. However, if you are using Physan as a disinfectant, I guess I don't understand why you'd be mixing the two together?????? I NEVER apply SA-20 with my fertilizer.... NEVER! I ALWAYS apply it as a separate spray because I really don't like the built up mineral look on the leaves when fertilizer gets on the leaves and dries.

As was mentioned, be ever so careful applying copper based products to your collection. It can be toxic in small concentrations to Dendrobiums and Gongoras...just my experience with it. Hope your rot clears up. It takes work, but I think it's worth the effort.
Thanks, also, for all of the input about Physan. I was unaware of some of the issues with it and will be more conscientious in my application of it in the future. I may have just gotten really lucky....:shock:

To answer your question the amount of Physan you would be using is not sufficient to change the PH of the water high PH is what inhibits micro nutrient absorption. Physan is an algaecide. It is the same product used in swimming pools to control algae. I use it to wash new bark but not for much else. I do not think it does much.

Very little will effect Nitrogen or potassium absorption and we should use much less phosphorus than is currently sold. MSU is basically a low phosphorus fertilizer mix.

As far as Phythion fungus is concerned (root rot) (fusarium fungus may also be present). I do not like any of the suggestions. I struggled with them all. Copper is not used by any other commercial grower, that I know and certainly not be me. It can easily build up toxic amounts with minimal effect on the fungus.

Clear 3336 is the old systemic anti-fungal, but it has been used so much and too often Now most forms of fungus are immune to it.

I have switched to natural bacterial products basically Bracillus subtilis bacteria. There is ample scientific evidence that it as as an anti fungal inoculate. It does not kill active fungal problems but after long term use 4-12 months the plants just resist the infections. I have gone from 8% losses to pythion fungus two years ago on my seedlings to less than 2% last year to none this year.

I use the Companion brand made from seaweed. There is now a second manufacturer making a very similar product under the brand name Thrive. The concentrations of addition ingredients are different but both are predominately Bracillus subtilis.

It is great to use as it is harmless to humans and pets. Then it is impossible to overdose with this product. I once sprayed it at 800 times too strong a dosage. The plants did fine.

Thanks for the info, Jerry.

wow and double wow. This is very precious info indeed. Just one thing missing: where do u get that 'companion' product?

lol a google search yielded only you as companion seller. Can u ship to canada?

I don't know for sure, but my guess is that it will slightly increase absorbtion of nutrients. My rationale is that Physan is a quaternary ammonium compound (I believe - if not - never mind). As such it will not only act as a bactericide, but will be a wetting agent. Wetting agents will improve the distribution of solutes (fertilizer) into and out of the medium. That may make them more available to the plant.

That's my theory. Even if it is correct, it probably isn't a major significant effect (or someone would have noted it long ago).

I thought physan contained sodium hypochlorite...at least that's what it smells like to me. Hmmm....

Googled it - here's the link to the Physan label

http://www.physan.com/PAGES/Physan20_8oz_Label.pdf

It is a quaternary ammonia. Sodium hypochlorite would be bleach - and a whole bunch cheaper.