Applied Biochemists 406303A Black Algaetrine Swimming Pool Algaecide & Deposit Control, 32 fl oz, White

After returning home after a long absence, I found that my chlorinator and pump had stopped working and I had a pool full of green and black algae. I started treatment with my usual green/black agaecide which killed the green algae, cleared the water, and got rid of most, but not all of the black algae that had formed on the bottom of the pool. The pool is gunite/pebblecrete which makes it more difficult to remove black algae. After several weeks of brushing and vacuuming, the bottom of the pool was improving but just marginally. I decided to try this algaecide to see if it could totally eliminate what looked like huge stained areas of the pool bottom. This algaecide is a totally different formula than my previous one, and unlike the other one, does not require super-chorination (shocking) of the pool when using. I used half the bottle in my 11.000 gallon pool in each of 2 applications a couple of weeks apart. It seems like it continues to work for 2-3 weeks after application, as every few days for several weeks I noticed the dark areas getting lighter. The key is being patient and brushing with a stainless steel brush every few days. After 2-1/2 months, the dark areas are almost completely gone and the bottom of my pool is back to the Caribbean Blue it's supposed to be.

Toward the end of the summer we developed a black-looking algae on the floor of our pool which had never happened before. Our usual algaecide didn't touch it and it wouldn't brush off. This product removed it all after just one application. I was pleasantly surprised and impressed. This is now a permanent staple in our pool supplies. 8/17/2014 update Be careful not to use this product too often. It has a high copper content which can build up and stain your liner. It happened to me and it took $200 worth of chemicals to remove the copper.

The first bottle the seller sent leaked out few oz in the box. Told the seller about it and they sent a whole new bottle. Great service; I highly recommend this seller! As for working miraculously on black algae (as some reviewers had written), the jury is still out. I have a 30' above ground pool and I followed all the instructions; even used double doses. After 3 weeks the back spots (black algae) were still there. They may have been diminished some but it wasn't noticeable so I got in with a nylon pot and pan scrubber (they look like a nylon version of steel wool) and scrubbed all of the spots off with my feet using those scrubbers. The nylon pot/pan scrubbers work great and won't harm your vinyl pool liner; the only way to go. I did notice that after the application of this stuff though, the algae did come off a lot easier and has stayed gone so far (knock on wood). Bottom line is that with the heavy infestation of black algae that we had, this product did not make it vanish over night... or even within 3 weeks (even after brushing it twice a day every day). Those reviewers who did say that this product made their black algae vanish over night or in days were either delusional or did NOT actually have black algae.

If you have black algae, this Copper based algaecide really helps - but it will not totally 100% eradicate the black algae by itself. After adding several quarts of copper algaecide and many pounds of the Chlorox shock w/ copper, I still had black algae on the floor of my pool - even though the water was perfectly crystal clear - in fact, this year my water is the clearest it has ever been! I found the solution to the black algae quite by accident. I bought a couple boxes of Trichlor shock. Trichlor has stabilizer in it so it dissolves much slower than Dichlor shock (and most "shock" is dichlor). The Trichlor is a bit cheaper - so I bought several boxes and figured it's give it a shot. WOW!! Instead of dissolving immediately, it falls to the bottom of the pool and just sits there....right on top of the black algae...and by the next day, the black algae is totally gone! I immediately started sprinkling the Trichlor shock on other areas of the floor where the black algae was growing -- and sure enough, bam! The next day it was gone. So in my experience, to get rid of black algae you need two things - Copper algaecide and Trichlor shock. Use the copper algaecide as directed on the bottle, and just be prepared to dump pound after pound of Trichlor shock evenly over the areas of black algae. You might need several treatments of the Trichlor, but believe me -- it does work.

I don't understand all of the good reviews. This didn't work for us at all. We didn't even have black algae, just some of the regular green stuff. Our pool is old and the walls are rough which means we do get some green algae growth in the rough surface which we can't easily brush off. So we followed the directions as given. We checked the water was balanced, it was perfect. We hired scuba tanks and got in there and scrubbed and scrubbed and scrubbed. Cleaned filter, vaccummed. Then we applied the product. Water went very cloudy. Ran the pump. Got in there again the next day - vacuumed, cleaned filter, and scrubbed and scrubbed and scrubbed, but none of the algae was dead or gone. The water was still very cloudy. Cleaned filter again, ran pump. Vaccumed again, cleaned filter again, scrubbed again. Water still very cloudy, no change to the algae. 3 days of hard work. Checked the water and wow, the alkalinity and PH are now off the chart! Took a water sample to the pool store and they advised us not to use the pool, it wasn't safe. We should change the water. So now we still have the algae in the rough surface, have spent 3 days on the pool, and the whole thing has to be drained and refilled. I'm so mad. How others are getting instant results with this stuff I don't know because it didn't work for us at all and cost us hundreds to drain and refill the pool.

I have learned since moving into a house with a pool over 25 years ago to get ahead of any algae bloom. If persistent brushing, keeping the chemicals perfect, and 24/7 running the pool doesn't work - this is the ONLY product I have found that will actually get you back to a sparkling pool. Pretty darn pricey though so believe me I try everything before I go to the Black Algaetrine and always have a bottle in the shed. A 38,000 gallon pool usually only takes one bottle - but I don't let it get emerald green in the first place.

This was my first experience with black algae and I have had an above ground pool for 12 years. We had a major storm and my best guess is that it was blown into the pool from somewhere else. Until this situation I have never had trouble with algae unless it was due to my own lack of attention and chlorine always took care of it. Chlorine does not touch black algae at all. Since I had no previous experience with it, I over-shocked my pool for 10 days and scrubbed and scrubbed but it never helped. That approach might work better with an in-ground pool but the algae acted as if it was glued to my liner because scrubbing never made a dent. So I did my research and settled on this product. I did not follow the recommended instructions which were to scrub before and after and apply in the early morning. I applied in the evening and never scrubbed at all. Within 2 days the black algae was all gone with only one treatment. Granted I did use more than I needed to but it did not make sense to leave so little left in the bottle. Since I did not want to swim with the chemical at full strength I applied it down the middle of my pool as I exited.

Great product..hot summer pool days just around the corner.