You're doing really great!!! I totally understand you're hubby's urge to drain and refill, but if you sit down and do the math, you'll have to re-add cya, adjust ph & TA, and then, of course, SLAM again anyway to sanitize the liner, pool equipment, and the new water. The choice is always up to you two, but my vote is finish what you started, only spend the money on bleach/liquid shock until you finish your SLAM, then let the FC drift back to normal target level for your cya and then readjust ph once again when it is under FC 10. I think you'll save more money and be swim-ready sooner if you stay the course. You've done so much and learned so much and are seeing the stuff on the bottom now! We're all proud of you! Any questions so far? Maybe hubby can help with the brushing if that's getting too much for you? It really does help to scratch up any leftover hardened algae and to mix the water thoroughly. You can also vacuum more often if you like, just be sure to leave a couple hours for the stuff to settle and vacuum really slowly to not make to many waves along the bottom when vacuuming that would stir it up before the suction gets there.
