If the wind blows like it does in OK, and you don't have enough blocks to go around the entire pool, they'll fall off the edge when the wind blows and pitches them off. Two of them have broken so I can only fill them about half way.
After fighting the typical prevaling north wind (20mph+ at least 50% of the time), we finally decided to use these on the ground to hold down a 2nd cover over the north end of our pool. For the last 3 yrs, we've fought the "jiffy pop" effect of the cover on the pool so we decided to use a 2nd cover overlapping the first, down to the ground. these blocks help hold that in place. So far, so good, but we'll see how it does after the whole winter.

(Posted on 12/22/10)

These are pretty good blocks. They are much better than the tubes that I would throw out every season. Two issues to keep in mind. Attach your blocks to the pool cover before filling them with water because they are very heavy after filling and the tops do not snap on so they just pop off. That's real annoying but its better than buying new tubes every year.

(Posted on 10/23/09)

Last year we purchased a few of these blocks for our 20'x40'in gound pool. We were so satified on both the application and the storage of them that we ordered more of them to complete our system this year! I would advise anyone that is using the tubes to change over to the blocks, especially if you have squirels and or other animals or pets that usually damage the tubes.

(Posted on 10/17/09)

Now, I realized that the waterbloks are an excellent product to have! It is now a lot easier to cover and uncover the pool! I had to throw away at least 6-8 balloons and buy new ones every year - not anymore! Excellent product!

(Posted on 10/5/09)

Got sick of replacing many balloons every year. So I decided to try out the blocks this year and starting to love it! A lot less hassle to fill, drain, clean and store, I just kicked myself for not buying it long ago!

(Posted on 9/29/09)

I purchased these two years ago, due to the fact that the water bags always sprouted leaks after every season. They held the cover down much more securely, but they were more difficult to maneuver to place them correctly around the pool. They were, though, easier to store for the summer because they stack out of the way. The covers popped off a few times the second winter, but were easily recovered.

(Posted on 8/22/09)

After years of replacing water bags, I decided to try these. The Aqua Bloks are so much easier to fill and clean up in the spring.

(Posted on 10/6/08)

After having struggled with water bags for many years, I began to look for a better solution. While the water bags certainly worked, I had ongoing problems with leaks and punctures, making it necessary to replace bags on a regular basis. I decided to try using Aqua Blocks and am very pleased with the results. Although Aqua Blocks have a five year warranty, mine still look and perform like new going into my ninth year of use (through long New England winters). I would highly recommend the use of Aqua Blocks as a much improved water bag alternative.

(Posted on 10/22/07)

I switched to Aqua blocks last year. The water bags didn't hold up well and these just seemed like a better idea. Very durable.

(Posted on 9/15/07)