Need help getting rid of algae

wonderphil-reef · Jun 2, 2026

Hi guys

I have struggled for the past 4 to 5 months to get rid of this algae and looking for some suggestions. My lfs suggested cover the tank turn off the light for 3 days to kill it, but didnt seem to do anything.

Water params are pretty stable and around:
Temp: 25c
Salinity: 1.025
pH: 8.1
No3: 2
PO4: 0.04
Alkalinity: 10
Cal: 430
Mg: 1300

Tank is about 1.5 years old

Thinking of taking all the rock out and replacing, but doesnt help my spf that is now full of this crap

FishyHotel · Jun 2, 2026

That is quite a bit of algae as you know. The problem with killing it all is once it has died the nutrients will return to the water and it will just grow again. I would start doing some manual removal and look at your phosphates/ nitrates to try and get those down. For anything like the wave maker, I would take it out of the tank and give it a soak in citric acid and then scrub it. You can also pull the algae off the rocks while doing a water change and use the siphon tube to suck it up.

If you are open to getting a creature to do some of the work for you an urchin will help - they really do a lot of work on algae. If you do end up getting an urchin just make sure you glue your frags down because they can move stuff around.

c4haskett · Jun 2, 2026

Turbo snails are great and so are urchins. The thor's hammer of algae eating is a sea hare. They are like goats. They will demolish all that algae in a blink of an eye. I would add in a handful of turbo's and an urchin first. If the algae still persists, get a sea hare. Once the algae is gone, you will need to sell/trade the sea hare immediately or else it will starve.

Mr. Mojo Rising · Jun 2, 2026

Not sure what you have tried, but the glass and the powerhead tells me that maintenance is lacking. A powerhead that looks like that is not providing much flow which worsens the problem. Do you have only one powerhead in the tank?

Lights out doesn't work, as mentioned above, any algae that would die will just release more nutrients feeding more algae. Personally I would strip the system of excess nutrients, clean all equipment, and ensure that filtration can handle the bioload and feeding. Its all about nutrient import vs nutrient export.

IF you can share more details about your system then we can help. Green hair algae is the easiest algae to get rid of IME, although it does take time and perseverance.