Backyard Aquaponics
A place to discuss aquaponics

Hi All,

I have an algae problem, infact its one of my cousins fish tank with Tilapia in India. There seems to be uncontrolled algae growth with in the fish tank. I could eliminate it totally by a water change and adding a shade. I should have added the shade earlier but did not. Now planing to, so i need to get rid of the algae first.

Would it be ok to add Sodium Silicate or calcium silicate to this water ? Are there any after effects on the fish or plants ? or is there better solution tot he problem without a water change ?

You have answered your own question

Yes stop light getting into tank (only need enough light to see dead fish / uneaten feed ect)

If you have lots of algae blocking your pump a total cleanout would be a good idea

If the algae is just growing on surfaces it will go away once light is restricted

I am trying to avoid a water change as its scarce at this time of the year. Is there anything else that could be done after the shade is put up ? Would adding a shade kill existing algae or lowering the Ph ?

Is it on the walls or suspended in the water? Is the system fairly new? If it's new, early algae blooms are fairly common and will clear. Resist the urge to treat the system or "add things".

Not new has been running for six months. He could not afford a shade for the fish tank so he covered the tank with tarpaulin when the sun came up. I guess he did not cover for some days which started the algae growth.

The water is just green nothing thread like. So I guess the algae is not too much.


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Most of my systems have been out in the open sun, never covered and would always stay crystal clear once they were a month or two old, just green algae on the side of the tank. If the water ever went green, it was a sign something in the system changed, pH dropped or similar.

Oh something new to learn. So would that mean algae growth begins at lower ph ?

How come algae did not grow in your tank even after leaving the tank in the open sun ? Was it away from direct sunlight ?


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I'm not sure what EB will say but I think the algae runs out of phosphorus once the plants in the grow beds get going. The only time I see algae blooms are when there is nitrogen and phosphorus available in the system water and I think the phosphorus gets tied up pretty fast.

Thought tilapia ate/filtered algae, why do you want it clear?

Well id on't it crystal clear just clear enough to see the fish.

Hello there Georget!

Might I suggest adding Duckweed to your cousin's pond? Duckweed is a wonderful source of nutrition for Tilapia and helps to fight algae. Yay!! Duckweed spreads quickly across bodies of water (as long as the fish don't eat it all up first) and will act as a blanket on top of the water. Not only will this inhibit algae growth and act as a food source for your fish, you can eat it too! Duckweed is a great source of nutrients for both fish, animals and humans. Now I am not sure how easy it will be to get Duckweed in India but here in the states it grows all over the place. Your cousin's fish will thank you for the shade from the hot sun and the clear water filtration that Duckweed provides.

Cheers friend!