This is a cut and paste of my response to this problem from the thread: "Desperate measures!!! Fed UP !!!!" The original poster was Crabby Jim. Sorry for your algae problems. I battled algae for about 20 years. Back in the day, heavy algae growth was a sign of a well-established tank. The fish didn't mind it a bit. If you don't have corals, and don't mind the ubiquitious green appearance of your tank; let things go. No biggie. Not funny one bit, eh? I've "pulled the plug" on algae lots. Turned off my lights for weeks at a time. Did copious water changes. Used every chemical additive in the market. I was at wit's end. I've tossed in the towel more times than I care to confess. Some say that turning the lights off will help. Been there. Deprived the tank (and fish) of food. Done that. Removed and scrubbed clean every piece of live rock in the tank. Tried that too. Do those 3 things and it will look like you never had algae in the first place--for about 2 weeks, until algae once again takes hold. There's so much advice about ridding your tank of algae that it seems redundant, doesn't it? Well, it's redundant because a lot of those tips work. If you take all the good tips, and incorporate them in your setup, you're literally guaranteed to win the algae battle. That's what I did. I decided that I'd try only those tips that I've read more than 50 times. LOL. Truth is, if you do the right thing, you can have your display tank in direct sunlight for an hour or so each day. You can even overfeed once in a while. The thing is, you must treat the cause. You must go in for the kill, and stop putting bandaids on the wound. Here's what I did: 1. I lost the crushed coral substrate and replaced it with sand. Turns out CC harbors all kinds of detritus, leading to nitrates, leading to algae. 2. I built a 10gal refugium, and put in chaetomorpha macroalgae. The fuge is lit when the main tank is not. It has a 55K "daylight" bulb. It's like sunlight overnight for the chaeto. The chaeto competes with tank algae by consuming the very same nutrients. The macroalgae is like the greedy relative who comes over and eats all your food. You're left hungry. 3. I stopped using tap water; and purchased a 5 stage RO/DI unit for $169. Seems that tap water saturates your tank with phosphates and silicates. Algae will thank you for those important nutrients. 4. Made sure my protein skimmer was a good one. Dissolved organics are high on the algae menu. 5. I purchased a phosphate reactor and run it 24/7 with the indicated amount of phosphate removal media, and packed the rest of the way with carbon. Carbon doesn't remove organic matter like protein skimmers, but it's pretty amazing how the variables come together and provide results you might not expect. Carbon keeps your water crystal clear, and since corals are photosynthetic, this helps them grow. Coralline algae (more coral than algae) love the light too. When corals and coralline algae grow, algae doesn't fare as well. Ever see a photo of a tank with tons of green algae and corals and corallines growing? Not even once, eh? By the way, it's important to run phosphate removal media in an ACTIVE way, like a chamber of some kind where water is forced through, rather than passively tossing a bag of the stuff in your sump. That doesn't do very much. 6. Took the bioballs out of my wet/dry. I did this because I read that bioballs are "nitrate factories." I think nowadays that clean bioballs are safe, and as long as detritus doesn't collect on them, nitrates won't have a chance. 7. I upgraded my lights, making sure that an old, tired bulb's wavelength ouput wasn't contributing to algal growth. Over my years of SW tank husbandry, I've done countless searches for "algae problems" and I've tried many of the tips espoused by people in the same boat. They seemed to make sense. It took me a long time to figure out that I needed to do all the above AT THE SAME TIME. My personal guarantee to you is, if you did an experiment and incorporated the seven points above, you won't see a speck of algae again. Hit the algae problem hard. Blitz it. Rob them of nutrients. Provide an inhospitable environment for algae. You will win. Good luck!