So we had pool people for about 8 months after getting tired of the Leslies "buy a bunch of this and bring another sample so we can tell you what else to buy tomorrow" run-around. But they stopped showing up and after a few weeks I had a green pool. I changed the DE in my filter, threw in some Leslies Power Powder that I still had, vacuumed the bottom, and got a nice clean pool. But I knew I was going to have chemical troubles again, so after some googling I found The Pool Calculator and Trouble Free Pool. I'm convinced, and I've been working on reducing my TA with acid and using liquid chlorinator (first I used Clorox, but the 10% chlorine at Lowe's was cheaper at $6/2 gallons).
Here are my numbers this morning:
pH: 7.4 (after taking it down to 7.0)
TA: 150 (down from over 200)
CYA: ~50 (I'm using an AquaCheck test strip for this since I don't have one of the recommended kits yet).
I added chlorine to bring FC back up to 5, but it keeps dropping low after a day or two. I thought maybe the high TA or the low pH were causing the quick drops, but after re-reading the shock section in Pool School I think the problem is probably excess organics still in the pool (although the water looks beautiful) and that I need to shock the pool and keep it shocked until it holds steady. Does this sound correct?
I'm guessing the nasty stuff is stuck in the filter, so would it be better to change my DE again? I always hated changing the DE, since I thought I had to take the thing apart and hose off the individual filter grids each time. Thankfully Pool School taught me that I can get an 80% change just by properly using my multi-port valve
One final story: I took a water sample into Leslies hoping they could get me CYA and CH numbers. The guy started the chlorine test (using the same DPD chlorine test I have at home) and asks if I've shocked the pool. I said "No, but I've added some chlorine" and he holds up his cruddy-looking test vial and says "look at this, your chlorine is at least 5, probably closer to 8, we can't test your water for you until it's down to 3." Of course, since I've been reading Pool School I actually wanted my FC at 5 or 6 so now I know that Leslies has nothing left to offer me. I said thanks and left the store.
My pool: 20,000 gallons, in-ground plaster.