I recently scored a 1200 gallon poly tank. I intend to use this to store rain water for watering my breeding
roses in the green house.
My big problem is how to stop the build up of algae in the water tank during the summer heat.
Are there any chemical that would help control algae without harming my potted roses
As long as the water is exposed to sunlight it won’t be possible to keep ahead of the algae without using chlorine or copper. You could bury the tank but, then again, what’s the harm of leaving the algae?
How about one of the UV treatment units? I don’t know how suitable it would be for this use but they use it to prevent algae in aquariums. Other than painting or burying the tank to eliminate light, adding chemicals or perhaps boiling the water, UV might help? I dunno.
Ordinary algae are not harmful. But my observation is that blue-greens (cyanobacteria) seem to have allelopathic toxins. they definitely steal iron from hydroponics. I doubt you could get enough UV to kill them. I feel really sorry for aquarium fish if they are being irradiated to try to kill algae. UV penetrates rather poorly. If your water is pure as tap water, nothing much will grow in it. I have gallon jugs over 10 years old in my greenhouse for thermal ballast. Capped, they stay clean, except for some biofilm on the bottom. But if you leave a trace of milk or orange juice in the jug it will get green.
If your tank is open at the top, get some cat-tails from a local bog and suspend them with roots in water. they will suck up nutrients. In warm season water hyacinth does well too.
Would a solar powered oxygenator help?
“But if you leave a trace of milk or orange juice in the jug it will get green.”
Green, then yellow, then a brown residue that fall at bottom. Neither do harm.
In my experience in controlling algae in my bird baths, I’ve just put in about 7 pre-1982 copper pennies. The result has been no algae all summer.
I had read somewhere years ago that copper was a natural algaecide. I suppose any form of copper would work, it doesn’t have to be pennies.
I don’t have the scientific background of most of the members of this Forum, so I cannot begin to tell you why this may work.
Smiles,
Lyn
I would like to thank everyone who weighed in on this subject.
I’m thinking of using this water for low pressure drip irrigating my roses in the field,I’m afraid that over time algae will plug up the hoses.
Burying the tank here in this environment is not practical without a lot of lateral reinforcing because of our severe winters.
I’ll have to research the use of Copper Sulphate more.
Copper Sulphate maybe accumulate in the pots and can be toxic to the roses
The best idea so far is to wrap the tank in a heavy grade tar paper and then indoor/outdoor carpet.
FWIW
I was plagued by iridescent green algae and feather algae in my 120 US gallon fresh water aquarium that contains various non-chiclid tropical fish and plants. The algae coated the tank sides, gravel, wood, piping, thermostats etc etc. Tried all the usual aquarium chemicals for nearly three years, water changes and algae eaters. Nothing controlled it. They got rid of aquarium algae-cide years ago.
So in desperation I began micro-dosing with 40% pool algae-cide about 3 months ago. I added 1/10 of a ml per 120 US gallons per week and continued normal water top up - no I never worked it ml/L (too lazy).
Completely under control and no fish or plant deaths. My water is hard with ph likely above 7.
It would work to throw in some submerged grasses, like anacharis, or floating plants, like duck weed or water hyacinth, that compete with algae for available nutrients in the water. There’s no magic to this as they are all weeds under good conditions. Hardy anacharis, if you can find it, drops to the floor of bodies of water in the winter to emerge again next year. Tender plants can be replaced each year or a piece can be overwintered indoors in a fish bowl. Any pet store or aquatic nursery should carry them. A combination of surface shade and depleted nutrients keeps algae at bay. The system is self-governing once introduced.
I purchased a product to purify and clarify my rainwater tanks which were used for storing diesel fuel before I started catching rainwater. But, and this is a big catch, the product is now quite expensive (in my opinion) but it is available on Amazon. They (ADYA) were involved in a lawsuit several yrs ago and at that point in time one or more of the ‘dealers’ sold all their on hand stock half price. So I tried it, and it works unbelievably well. It is a little difficult to get past the hype and the name calling on several sites (you can still read all this on the net–but they won their lawsuit, and the product does work for keeping the water pristine). The product is called ADYA Clarity which is supposedly from a Japanese process using black mica. I do not use as much as they recommend but the water is clear and odorless after sitting for approx. 6 months to a yr. for the last 2,3 yrs. This is roof runoff which is not all that clean either, but I take care not to catch the first rain of the season. I only have enough left for possibly this yr and the next, after which time perhaps I’ll use a few copper pennies. If you go to their site note how much they recommend to use. I used one cup per 50 gals of water and it worked well here in Ca., with the water tank in the sun for at least one half of the day and not being super clear when it comes off the roof. This water has only been used on the roses and the odor and film from the diesel fuel disappeared the first time I used the clarifying stuff and I had been unable to get rid of it any other way, which I had tried by using industrial cleaning detergents by Chevron.