A Community and Forum For Aquaponic Gardeners

getting rid of algea

We have our system in an enclosed green house and was wondering if anyone has any helpful tips on how to get rid of algea. It's in the tanks, growbeds and even the greenhouse cover. Does anyone know of a fish and plant friendly way to get rid of the algea?

0 members like this

Replies to This Discussion

Permalink Reply by TCLynx on February 25, 2014 at 9:03am

Cover the fish tanks to block the light from the water.

Make sure in the grow beds that you are not flooding over the media so that most of the water is protected from the light.

If grow beds are translucent, then wrap up the outside or paint the outside to protect the plastic from the sun to keep algae from growing inside them and to keep the UV light from making the plastic brittle over time.

As for the greenhouse film, scrub off the outside so it is clean. Make sure water can't pond or collect on the covering and keep the covering clean/dry to keep algae from growing on the greenhouse cover.

There are no good chemical ways to get rid of algae that won't also hurt your fish/plants. Algae is a plant. You can sometimes darken the water to inhibit algae in the water some but it is usually better to simply block the light from your fish tanks.

Now a thin film of surface algae is normally not a problem inside tanks or beds. Sure algae will use up some of your plant nutrients but a very thin green surface algae is normally not enough to be a problem. It is when the algae turns your water green so you can't see the bottom clearly then that can become a big problem quick. Also thick mats of string or floating algae can be a major problem since it can create layers of decomposing stuff you don't notice or they clog pumps, drains, and grates or it then dies and becomes thick mats of decomposing stuff in your tanks and can rob oxygen from your bacteria, plants and fish and possibly even elevate pH to the extreme.

Permalink Reply by Jim Fisk on February 25, 2014 at 9:07am

I'll post the same answer here:

Hi Bob, Is the algae turning the system water bright green or is it just showing up in areas where the sun is hitting? The dark green algae that grows on your fish tanks for example is doing no harm but only good and even my trout enjoy munching on it at times. If your water is opaque with bright green algae the main concern is if that colony suddenly dies off you could go into oxygen depletion resulting in fish deaths.

We really need pictures or a better description in order to help. When my 2000+g system went bright green a year or so ago I simply made a Polyfil (Walmart 10.00) filter out of a 30G barrel (in stock) and a diaper hopper (9.00) from the Dollar Store and by just running the "bypass water" thru that filter the system was completely cleared up in only 2 days. I posted pics and info at my page back then with description. Just click my avatar and ck it out IF that is what you are talking about. There are numerous other methods including installing a UV filter in line that will do the same thing by genetically damaging the algae's ability to reproduce. I like the polyfil filter best as it is very cheap to build, about 20.00 and physically removes the algae on the spot. All you do when the system water clears is shut down the filter and wash out or throw out the filter media.

Keep in mind your system water should see as little daylight as possible for starters. Water level in the beds should be about 2" below the media surface. Prevention goes a long ways.

I tried to upload some pics of the filter but the uploader is crashing so go to my photo page and find pics there.

Permalink Reply by Jim Fisk on February 25, 2014 at 9:16am

Hey, the uploader is working again: Here is the filter:From this:

To this in 2 days:

Permalink Reply by Jeff S on February 25, 2014 at 9:39am

I went to the pet store and bought a Pleco fish $3-$5. Worked wonders in my tank. Cover the tank at least to keep evaporation down and humidity down in your GH.

Permalink Reply by TCLynx on February 25, 2014 at 9:50am

Pleco will eat algae off surfaces but they won't filter feed on green water.

Permalink Reply by Max Gfx on February 25, 2014 at 11:40am

I use Plecos to keep surfaces clean, but I also shade my tank and add kelp extract (Maxicrop) on a regular basis to tint my water brown which blocks blue light. One of those things I remembered from my optician days, brown lenses block glare (blue light). Block blue light in your water and the algae eventually dies off because it can't photosynthesize.

Permalink Reply by Jeff S on February 25, 2014 at 2:34pm

My Pleco must be hungry. He was eating fish food off the surface water just this morning. No algae left in the tank. If I put him in my duckweed tank will he eat the duckweed or just the algae?

TCLynx said:

Pleco will eat algae off surfaces but they won't filter feed on green water.

Permalink Reply by TCLynx on February 25, 2014 at 3:30pm

Pleco will adjust their diet to an extent based on age and what food is available. My understanding is when they are young and small they prefer to scrape algae off surfaces and plants but as they get older they are more likely to eat pellets and food that sinks but if they are hungry and/or their preferred food isn't available, they are going to eat whatever they can. I really don't know if they are likely to try to eat duckweed off the surface of the water in preference to algae but obviously if yours is able to eat pellet feed from the surface of the water when the algae is gone, they probably could eat duckweed from the surface if they were hungry enough. If you want to keep them from eating the duckweed you might have to see if there is some pellet feed they like better than duckweed.

FYI Tilapia Can as adults filter feed on green water type algae in addition to eating string and surface algae and they will also eat duckweed. I do know that if you want to grow out tilapia that you shouldn't expect them to eat more than about 50% of their diet as duckweed or they tend to loose weight. I had a duckweed tank that was 16 foot long and 2 foot wide and I put about 6 breeding age tilapia in it. If I fed them a hand full of pellets every day, the surface of the tank remained well covered in duckweed. If I didn't feed them any pellets for 7 days, they would totally consume all the duckweed in less than 7 days and be hungry, the duckweed couldn't keep ahead of them when they were all living in the same tank with no other source of food or fertilizer.

Permalink Reply by Jeff S on February 25, 2014 at 3:35pm

I'll let you know what happens.

TCLynx said:

Pleco will adjust their diet to an extent based on age and what food is available. My understanding is when they are young and small they prefer to scrape algae off surfaces and plants but as they get older they are more likely to eat pellets and food that sinks but if they are hungry and/or their preferred food isn't available, they are going to eat whatever they can. I really don't know if they are likely to try to eat duckweed off the surface of the water in preference to algae but obviously if yours is able to eat pellet feed from the surface of the water when the algae is gone, they probably could eat duckweed from the surface if they were hungry enough. If you want to keep them from eating the duckweed you might have to see if there is some pellet feed they like better than duckweed.