I have tried different methods and I haven't figured out which is best for me. In the past I tried hydrogen peroxide. This year I tried just a spray of water and a good brush, followed by a CAREFUL spray of 1:10 bleach and rinse, which I decided was faster and more thorough than the peroxide. SB

How about sealing the ends of those channels with aluminum tape? Works for me.

Yikes! Please, somebody- anybody! How to prevent that mess to begin with?

My polycarb panels are sealed at the bottom. Will that make a difference, as gardenstate suggests?

Also, I've been meaning to ask, because eventually, it will need it: What is a safe cleaning product for the exterior of my polycarb?

We use a pressure sprayer to wash down our vinyl sided house and for real dirt, especially on the white painted aluminum gutters, a soft brush dipped into a solution of warm water & ammonia works very well.

Would the same be safe for the polycarb? I know better than to use the same level of water pressure, but surely, a wash down with something to loosen accumulated dirt will be necessary: but with what product?

I must have been blessed this year - cleaning was a breeze. Emptied everything out of the GH, washed it down with that 1:10 bleach solution and rinsed right away, and left it in the sun to dry while I washed down the inside with the same solution, also rinsed right away. Washed the outside like a car, using a sponge on the wall panels and long-handled soft car wash brush for the roof panels, then rinsed down.

The worst part was the rain gutters, which needed a good wipe-down inside, and getting rid of all the spider webs ... I know they're good critters, but they still make me shudder.

Wish I'd thought to take some "before" pics, because it looked pretty clean and there was absolutely no visible mold or algae anywhere on or in the panels - surprising, because they, and moss, seem pretty vigorous in our warm, humid weather just a few miles from the NJ shore and a bay across the street. And, sitting under a huge limbed-up oak, it gets dappled shade from noon on all summer long. Nevertheless, by comparison, it really did sparkle like new when all clean.

The outside of the south-facing roof panels will be cleaned after frost takes out the moonflower vine; for now, the added shade it provides is still welcome.

While the GH was empty, I pulled the gravel away from the foundation walls and installed an aluminum-faced, heavy-duty bubble wrap to stop drafts, then piled the gravel back on top. Then pulled the gravel away from the center, spread some levelling sand and placed a pathway of patio blocks three wide. It feels like new! Replaced the benches, shelves, hanging bars, etc., and, of course, the chair. Now starting to put a few plants inside, though our first frost date isn't until Oct. 31.

Javan, what an awful mess and how tedious it must have been to clean it! Thank you for sharing. I'm curious how long you've had your greenhouse ... basically, how long did it take to get like that? Maybe my GH is still too new and in a couple of years I'll be facing the same ugly mess.

Diane

I was going to ask about this too -- the greenhouse we bought apparently did not have sealed polycarb panels. I can't see all of them, but readily see the roof edges - there is the same black gunk -- it's only about 1/4 inch wide, so won't be hard to clean I think.

Has anyone had any experience sealing panels that were previously unsealed and slightly dirty in some parts? One panel has a spiderweb w/ a dead spider at about knee height.

Luckily most of the panels are not dirty inside.

We are planning on using a compressor as Nathan suggested, to clean out the panels before rebuilding.

I too was wondering if bleach or other cleaning solutions would be harmful to the panels.

Another question I had -- some of the panels have water stain buildup. Is it possible to use CLR on them with a soft brush?

thanks
pb

The pictures above are from my greenhouse constructed almost exactly a year ago, so the gunk built up pretty quickly around here. I liked the tips about the bleach solution. I have to do the inside of mine soon, but the hydroponic tomatoes are still going. Jim

That's interesting - mine went up in November of last year, so they've been up and running a similar length of time. After seeing your photos, I'll we watching out for that, and I expect others will be doing the same.

Di

Be careful with bleach! While I've never used it on my glazing, I did add a weak bleach solution into my plastic (polyethylene?) water tanks inside the greenhouse that I use to control algae growth (my first tanks were clear; I didn't take the time to paint tanks until this year). A year later, they were very brittle, brittle enough that I could break them easily.

I certainly wouldn't apply any bleach solution to the glazing. If I felt it necessary, I'd make sure that I washed it very thoroughly afterwards.

As we've discussed elsewhere, bleach + polycarbonate = bisphenol-A, a nasty poison.

My GH is tempered glass, not polycarbonate. I agree with the bleach/PC concerns above.

I'm certainly open to any other cleaning solutions safe and effective for polycarbonate for next year - don't want to ruin either my greenhouse or my health. However, the job had to be done, and knowing in the back of my mind that there were concerns, I made it a quick swish with a big car-washing-type sponge and rinsed it down thoroughly right away ... didn't let it sit and soak.

Like Javan, I'd really like to hear what others have used, on what materials, and how effective has it been?

Thanks, Javan, for starting a good thread.

Di

Nathan: Thank's for the heads up on the effect of bleach on the polycarb.

I'll make a special point to be careful with it in my GH, as I use a bleach solution to clean my fish tanks and equipment, and plant pots.

Would ammonia harm the polycarb? What about TSP?

If sealing the channels with aluminum tape will avoid that algae then I'm having DH take it apart and do it!

Last time we talked abuot this, someone found a list, which I put on wikipedia:
http://en.wikipedia.org/wiki/Polycarbonate#Interaction_with_other_chemicals

Ummmmm, I just read that article and list ... thank you Nathan for the reference ... and I'm really, really biting my tongue here(actually, my fingers) to avoid posting a tongue-in-cheek response that might get me in hot water, or at least cause readers to think me not quite a lady ;-)

Di

So.... when my poly panels are ready to clean, what should I use??? I'm more confused about that now than I was when I first read this thread :)

Nathan - what do you use?

pb

My panels don't grow algae, so I just use a microfibre cloth and soapy water.

My wife and I use Physan 20 generally in sanitizing our hothouse, trays, 6 packs, etc. We will be washing down the inside of our greenhouse with it soon. It seems to work really well. We learned about it when taking a hort propagation class at Cabrillo College near Santa Cruz. I have no connection with the company except as a product user. Jim
The following is taken from the physan website:

The Product

PHYSAN 20Â 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.

PHYSAN 20 is an EPA approved concentrate formulated with unique germicidal agents to provide overall protection for your plants and greenhouses.

PHYSAN 20 poses no human or environmental risk when it is used at recommended use levels and according to label instructions.

PHYSAN 20 controls disease-spreading organisms which can be carried from plant to plant by using contaminated pots, flats, seed beds, soil, tools and human hands.

Here is a link that might be useful: Physan information

I did a washdown of the greenhouse yesterday (both exterior and interior) with physan 20 and water. In reading the directions, it notes that physan is not for use around edible crops. I'm not sure why, but I will do some research. Clean away, greenhouse owners! Jim

I wash mine once a year with Palmolive dish soap and hot water. Gets all the algae off and it's safe.

Be careful with your polycarbonate! Mild detergent is probably OK, but the UV protection on polycarbone is a coating on the outside. If that coating is damaged, the panels are no longer protected from the sun. It's worth the time and energy to treat this stuff with extra care, expecaily since you can't see the coating or know if you've damaged it. If you treat it lovingly it will last for years, but you have to be careful.

Would aluminum tape on the panels prevent buildup like that accululating? Or make it worse?

heebiejeebie, that aluminum tape question is a good one. I may try to tape a couple of panes to see if it makes any difference. I enjoy experimenting. Jim

You don't want to seal the bottom edge of the panels with aluminum tape since that will cause condenstation to collect and build up in the channels. Bottom sealing is done to prevent dirt, dust and insects from from entering the channcels. Use a fiber type tape (sometimes called anti-dust tape) that allows the channels to breathe.

Thanks for the tip gbrendemuehl. I'll pick up some anti-dust tape and try that. Jim

The manufacturer recommended cleaning agent for polycarbonate is vinegar- acetic acid. Not recommended is ammonia, because of its effect on the UV protection. Bromine, sold as Agribrom, is registered for use in greenhouses for control of algae, whereas chlorine is not. With either bromine or chlorine, the effects on the UV protective coating of polycarbonate is not adequately researched, so use with caution. It would be very difficult for hobby growers to determine if the UV protection was damaged or not.

As a follow-up recommendation, the bromine product should not be used directly on the polycarbonate, nor should chlorine. The bromine is an option for benches, under benches, etc. It is not phytotoxic for the plants that have been tested, but with the very wide variety of plants in our greenhouses, again, use caution. Vinegar however, would be the agent of choice for cleaning polycarbonate.

Based on the emails received, please see the web link attached for a list of plants tested in the phytotoxicity trial with bromine.

Here is a link that might be useful: plants tested with agribrome

Here is a link to a page with Polycarbonate Cleaning Tips. Google it and I am sure you will find more

Here is a link that might be useful: Polycarbonate Cleaning Tips

Building and maintening a backyard greenhouse is no easy task. My tiny little greenhouse takes 50% of my gardening time in 3 seasons but early spring which often turns out to be a full time work. If you ever think of buidling your own greenhouse, do some serious planning before you start.

Here is a link that might be useful: The Greenhouse that Wouldn't Lie Down

Hi I have just removed the anti-dust tape from the ends of the conservatory poly carbonate roof as the TAPE was thick with dirt, moss and other growth which accumulates every year of the five years age of the conservatory an absolute dirt trap the reason for removal also cleaning the bottom of the poly carbonate roofing to remove the dirt etc that had penetrated.

I am now considering whether to replace or not as it seems the tape is just a dirt trap and courses much work annually to keep clean as after only a couple of months you can see the build up of dirt again.

Has anybody a solution to this as I can't see others having this problem?

Would leaving the anti-dust tape off cause bigger problems but would this attract insects to enter? The Poly carbonate is 35mm 6 honeycombed.

Thank you for your advice.

My greenhouse is only 1 year old. When I put it together I used aluminum tape on the top (upper) edges of all panels & I used breathable medical tape on the bottom edges of the panel. So far the panels are clean & I get no condensation on the inside of the panels