Bob, it does sound like you need to get a handle on good water balance and Algae control will come with that. Proper and consistent levels of FC and manageable levels of CYA is key. That said, I have a lot of experience with that very filter and it will not get all the fine sand, even when you vacuum, so don't have your hopes up. They work pretty well, but they are so small they have inherent limitations. Once you get a handle on the water balance, I have a suggestion that will cure any sand issues you may have. I like what you've done here, and you are clearly a man who loves his dogs. Pretty cool design and setup you have there, and I remember this from earlier this year.