Was using a small 15ltr bucket as a res, it was clear and green algae started forming.

It was because the bucket was clear and the HID light was helping the algae form, right?

Oh and thank you to everyone that recommended coco; quite frankly it's the gonads!

hey man, i'm new to hydro grow but i have LOTS of xp in growing shrooms and exotic fish, so i could recomend u that allways remember that: STANDING WATER+LIGHTS=ALGAE
the source of the algae is from the minirals that comes naturaly with the water and passed around in air (algae spores), the best way to keep your water is in a seeled to light tank and closed by lid.
any way if u can just change the water in the tank, but b4 u do it make sure to dispose of the algae by cleaning it, also u can use products such as "Algae Free" that u can find in any pet store.....
best of luck
PEACE&LOVE

If you can only get clear buckets, use 2 and put bin liners or panda plastic between them. Cheaper and easier than using paint or tape. For algae on the top on the medium where the plant is growing, I just ignore it, never had a problem with it and it recedes once the canopy grows enough to block the light.

15L for a res? That's about the smallest I've heard of.

Cheers lads.

Yeh, I know 15l is very small, but I have a very small space. Bonus is it's nice and easy to refill.

Good call on covering, just remembered I have a big roll of B&W that's not being used.