Tiny Air Bobbles On the Rocks Under Algae

Question
Hi.
I have brown algae problem plus, recently, I can see a lot of bobbles under the algae on the rocks. The algae is hair-like brown algae and sometimes real tall! All the parameters are perfect. I test them around 24 hrs after every water change which is once a week ( min 5% for the thank (see below)). As well, I add at least +2 gal every 2 or 3 nights due to evaporation. Is this a bad sign? My fish and corals seem to be very healthy.
Tank: 32 gal, 25 lbs live rock, real soft white sand 1.5 inch, a big hammer coral, a small Frogspawn, Elephant ear and green star polyp, yellow eye tang, sixline wrasse, yellow wrasse, 2 clown fish and a red flame angle and a blood shrimp (all small), 96 watt + blue moon light (10'000 K and Actinic T5s). Tank is 18 inches deep. I have protein skimmer for a 100 gal tank, canister filter (Fluval 305) and filter/power head...
I added the corals after about a year when I set up the tank. The rock were cured and were there from the beginning. It seems to be very stable with no noticeable variance in the parameters.
I never had this much algae problem before. Could it be due to the light that I added for the corals? Or the additives for the corals (Calcium...)?

Answer
Hi Reza,

Great question. Sounds as if you are taking really good care of your aquarium.

My recommendation is to thoroughly test your aquarium water for phosphates.

Algae needs phosphates to feed off of in order to grow. Even though all your water parameters are good, you will not know what your phosphate levels are unless you test for this separately.

Once you determine if you have a high level of phosphates, you can then take the necessary measures to get your levels down. These measures include finding the sources of exactly what is adding these high levels of phosphates. This could include your top-off water (this is usually the case if you are not using Reverse Osmosis water), certain fish foods, and certain water additives.

Regards,
David

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