So I just wanted to post something to thank all of our senior posters for their knowledge/wisdom in pool chemistry/maintenance. I've been a follower of this forum since last year; dutifully following the advice and principles found here.
When I closed my pool last year it was right before I had a bout of mustard algae; I used some Yellow-Out (bromine) to fight it off as I only had 4-5 days before my pool was scheduled to be closed up. Long story short the mustard algae went away but I had the surprising realization that the additive was eating all my chlorine up. I was able to get my pool to hold chlorine (after shocking but NOT slamming) a little by the time the cover went on.
Needless to say I'm pretty sure my chlorine was still being consumed after the fact. I pulled my safety cover (95% UV block) back to find a green floor and very grey/cloudy water. 6' deep end I could see the bottom but it wasn't pretty.
So - off to my first SLAM. I do have the TF-100 test kit and I know how to use it.
In preparation I added water to the pool so I could vacuum out the bottom to waste. I had to do that maybe 3 times as the water kept going below my skimmers before I was as far as I could get it. I was able to get maybe 85% of it out that way, however some areas weren't letting go w/o brushing - which suspended all the gunk into the water. My pH read lower than 6.8 so I raised it to 7.0. I know acidic water helps the chlorine be more active so I didn't want to raise it further. I figured another week or so at that level wasn't going to hurt anything.
I have a SWG but I wasn't using it yet. My salt was low but I knew I'd be backwashing and pumping more water out into the woods so I didn't bother with it yet. My CYA was 0 (from 70 last year). I added liquid conditioner to get the CYA up to 30-40. Tested with the kit; I filled the bottle with pool water and put it in my jean pocket to warm it up while I was futzing with other things around the pool.
I used cal-hypo to shock.
Shocked the first night to SLAM levels and lost all of it by the following morning. Not really surprising. The second night I lost 3/4 of it, the third night I lost a little less than half, so on and so forth until one week later. Crystal clear water, no chlorine loss over night, 0 CC. About 5 days in I added 200 pounds of salt to get my PPM up to ~3200; kicked on the SWG to help me hold my shock level now that I wasn't backwashing as much. VERY happy with my first successful SLAM. I brushed the walls and floor of the pool every day, just like you guys advised. For a couple of those days I even had the pool light floating in the water so the shock could get behind the light.
Some things that I learned from my situation:
A. Fill the pool up to above the skimmer when you're vacuuming to waste. Save some time with the back and forth and try to get more done.
B. The cal-hypo I bought ahead of time was almost completely gone by the time I was done. Next spring, double or triple the order.
C. This pool brush with the whale fin on it is a winner. Makes brushing so much more effective and easier. http://www.amazon.com/Wall-Whale-Cla...fin+pool+brush
Unrelated to SLAM'ing; I was obsessed with my pump pressure for a full afternoon. It was reading high even after a backwash. I was playing w/ my return jets and valves, plugging returns to see if there was air somewhere, etc. Than one night while watching TV it hit me. If I put my pump on backwash, I should drop all pressure in there. Is my gauge reading 0? NOPE. I was reading 4-5. So I took the gauge off; same thing. Mental note: Make sure the gauge 0's out when the pump is off and have a spare gauge on hand. Saves a lot of time.
Next up on my list:
A. Get my CYA up to 70 (I prefer the liquid conditioner b/c our pool season is pretty short compared to some of you and I'm impatient)
B. Add salt to get my PPM up to ~3400. I add salt last as the liquid conditioner is a sodium product.
C. Let my chlorine drift to 5 based on my CYA of 70. http://www.troublefreepool.com/conte...art-slam-shock
C. Lower my TA via a muriatic acid drop and aeration. I plan on using this to aerate: http://www.amazon.com/Splash-Round-P...=ATVPDKIKX0DER
D. Pop a beer, admire my work, and pray for warmer weather !!!