Algae growth within 1-2 days after presumably shocking the pool using 1 lb dichlor powder (3 bags total)
Since my pool is surrounded by oak trees, it usually starts the year (Feb/Mar) as a 25,000 gallon "petri dish". While removing leaves and cleaning filters 3-4x/week, I more or less used a combination of dichloc pool shock (more) and liquid chlorine bleach (less) and a liquid algae control product (3M product I purchased at Costco, sorry can't remember more than that about the algae control stuff). During this period I didn't take any measurements and relied on visual signs of improvement). Within 2-3 weeks, I could clearly see the bottom of the pool. In preparation to open the pool for the season in late Apr or early May, I added a water clarifier, increased pump runtime to finish cleaning the water, and continued shocking with mostly dichlor shock packages (3 packages 1x/week). (Test strips at this point indicated TC > 10 ppm, pH 7.5, TA 80 or lower) I use 2 pool floats, each filled with three 3-inch tabs for chlorine maintenance. (Can't say I test during the week, but my test strip always indicated zero chlorine before I started the weekly shock treatment). As the summer has gone on, especially with the high heat in the Western USA right now, algae growth has started to appear within a day or two after adding the dichlor.
I started seeking advice from several local pool stores a few weeks ago. One store had me treat for phosphates (>300), but that didn't seem to help. A second store indicated phosphates were still high (>300), additionally I had high nitrates (30), and their recommendation was to drain 30% of the pool water. Feeling frustrated, I searched the Internet and found the forums on this website. After a night of reading other posts, my immediate conclusions were to order the TF-100 test kit and that I needed to cease using any form of chlorine other than liquid bleach! So a few days ago I received the TF-100 test kit and ran a set of tests shortly after adding a gallon of 12.5% liquid chlorine:
FC = 3.5
CC = 1
pH = 7.2
TA = 200 (my test strip still reads 80)
CYA = 100 or higher (* See note below)
Based on the high CYA level, I went ahead and drained roughly 40% of the pool water. While the pool was draining, I opened up the pool light niches since a lot of the algae growth appears around the lights. I cleaned them out and they were full of green algae. I also partially scrubbed my pool walls in the areas where the algae shows up regularly. I re-filled the pool last night and did the following tests:
FC = 2
CC = 1
pH = 7.3 to 7.4
TA = 120
CYA = 70 (* See note below)
CH = 350
I debated with myself about adjusting the pH with borax, but decided to just add liquid chlorine. After adding ~5.5 bottles of 12.5% chlorine, the FC = 37.
I ran the chlorine test again this morning, FC = 20; and CC = 1, so I added more 3 more gallons of the chlorine which brought the FC back up to 34.
Am I on the right track? Are there any adjustments I should make to my game plan?
When do I know I'm done with the chlorine shock process? I'm assuming I'm looking to see CC < 0.5 and the fall in FC < 3-4 ppm/day. Is that right?
Being a rookie with the CYA test, I question my CYA test results. I think I need to run the test with better lighting, because I'm not sure I see the black dot or a reflection. Are there any posts in the forums with advice or tips about conducting the CYA test?
Thanks in advance! I'm glad I found you guys!!