Preventing Algae growth in water tanks

In an effort to keep water usage to a minimum, I'm getting 2 55 gal barrels. I'll fill one with water, the other empty. When it's time to chill the batch, I'll pump from one barrel, through the plate chiller, into the other barrel. I want to keep that water from getting nasty. Any ideas? Bleach is out as it's going through a copper and stainless plate chiller. Ideally I could treat once in the spring when I fill it the barrel and leave it for the summer.

After I've run the 55 gallons through the chiller, I can put the pump in a bucket of ice water and bring the batch down to wherever I need it.

 

You'll not get much algae, if it gets no sunlight.
You will be filling it with.....Tap water?
If so, that should be treated well enough to make an annual change-out of the water interval.
I have a 300 gallon "tote" that I capture rain water in, and before I put it into service, I removed the cage, scrubbed the exterior good with some Simple green, ( using a hand Scotch-Brite pad), and painted it satin black Rustoleum, with a roller and a brush.
The black blocks the sunlight, and when I peer inside it with a strong light, I see no algae.

 

High concentration hydrogen peroxide could be a solution. I use ~3 mL per gallon of 29% a couple times a month to keep my hydroponic system algae free. Shouldn't be a problem with copper or stainless.

 

Why not just use regular antifreeze? People use it with computer liquid cooling setups all the time. Perfectly fine with copper and prevents algae. Obviously, you'll need to be mindful not to get it in your wort.

 

This is the direction I want to go, should be able to chill it down past the brine solution I recirc now. Now they have non-toxic stuff as well. Has anyone gone this route?

 

I haven't even done a setup like this for chilling wort but I have done a computer water cooled system, which sounds similar. What most people do now is use distilled water with an algaecide. You can find it in any pet supply store in the aquarium section.

I ran antifreeze however a lot of people ran pure distilled because it cools better. I don't think you'll need to worry about the cooling capacity of your solution though, the computer thing is more because it's under constant load. I would suggest antifreeze as long as it's a carefully sealed system. I believe that breweries use glycol systems to regulate temps anyways.

There is also a thing called a kill coil, which is a silver coil that inhibits the growth of bacteria. The coil also acts as an anode to prevent corrosion to other metals in your system. Dissimilar metals, even some stainless alloys, will corrode if left in a solution together. The silver will give itself up and prevent this. Or just make sure that your chiller isn't in contact with the main body of water and you should be fine.

 

I forgot to empty the rinse water from my cooler mash tun. It has a copper manifold in the bottom. Weeks later, when I realized I didn't empty it, I was surprised that the water didn't have anything growing in it. I know some swimming pools use copper as an algecide. I wonder if I got the same effect, and if it would work for your tank.