(02/09/2008) - Have been using this for about a year and all I can say is great design. I use the threaded opening at the top to dump water out of the unit and refill. The only time you need to unscrew the entire top is to clean out the tubing every few months. The entire unit is easy to maintain to include the pump...if it wears out or starts to make noise, very easy to replace/clean. I run all top-off threw this unit ~2-3 gal per day over the past year. pump comes on 4 times a day for 10 min. Over the year, I have had to change the impeller in the pump but no big deal and easy to find at LFS in an emergency....can also use a mj600 impeller if cant find a mj400.

(04/28/2007) - I purchased this product about 8 months ago works great and as promised. Does help alot with keeping my PH in check with a calcium reactor and also keeping my cal and kh up also. Only reason i would liked to have bought the geo kalk reactor is because of the ability to drain the water from the kalkreactor without having to open top and undo all those screws and gently pour the water out. other then that it works flawless