Algae, probably need a SLAM

Longridge

New member
Aug 2, 2024
3
Los Angeles, CA
Pool Size
18000
Surface
Plaster
Chlorine
Liquid Chlorine
Hi all, I am extremely new to pool maintenance (we had a pool servicer for our first three years in this home, and my husband took over maintenance last year, but he's out of town and now I have to deal with an algae issue despite knowing nothing about pools). Apologies for the lengthy post, but expect more details are better.

Context: While we were gone for a few days, the pool pump stopped working for an unknown period of time, but our guess is 1-2 days. In that time, algae built up along the floor and walls of the pool. I found a pool technician to get the pump up and running, but he didn't do any actual maintenance on the pool to get it back into balance. That was about a week ago, and as you'll see from my test results below, things are totally out of whack at the moment.

What I've Done So Far: (day 0 = the day the pump was back up and running, but I wasn't home until day 2, so couldn't do anything until then)
  • Day 0: My husband cleaned the cartridge filters
  • Day 2: Poured in ~10oz of Algaecide (didn't measure, this was before I realized how important these kind of details were!)
  • Day 2: Added 1lb of shock; made sure the chlorine floater was full of chlorine tabs (have kept it full since ... realize now that this was not the priority)
  • Day 2 and since: Brushed the sides of the pool to remove any visible algae. Did one big initial brushing, and have been brushing periodically.
  • Day 2 and since: Used the vacuum robot (Dolphin Triton PS with the ultrafine filters) 1-2x/day (hosing it down after each use).
  • Day 3: Went to the pool store (only to later realize that was a mistake), had them test the water, and got the following results from the store:
    • FC: 0.54
    • TC: 0.54
    • pH: 7.2
    • Total Alkalinity: 4 (but "adjusted" due to effect of CYA on tested TA)
    • Calcium Hardness: 177
    • Cyanuric Acid: 111
    • Iron: 0.1
    • Copper: 0.2
    • Phosphates: 1070
    • TDS (?): 1200
  • Day 3: Was a sucker and bought from the pool store and used: NoPhos (1 48oz bottle), AlkalinityUp (1lb). The pool store guy said that because we use the Clorox tri-chlor tablets, we wouldn't need liquid chlorine (why did I listen to this guy!), so I bought Clorox sodium dichlor shock instead (Shock XtraBlue+).
  • Day 4: Used a second bottle of NoPhos (i feel sufficiently shamed about this, fear not).
  • Day 4: Added 1lb shock
  • Day 5: Ordered a test kit and more shock (I had really taken to heart that comment about our pool not needing liquid chlorine!)
  • Day 7: Test kit and shock arrived
  • Day 8 (today): Used test kit for the first time (and thus definitely might have screwed some things up but, this is what I recorded):
    • FC: 4.0
    • CC: [? I ran the test, but was recording all my info in the PoolMath app, which didn't have a CC input, and i don't remember what it measured]
    • pH: 4.9 (not sure i did the calculation on this right. The liquid was bright yellow, far below the visible color scale. I needed 12 drops to get it to 7.4)
    • TA: 70ppm
    • CYA: >100 ppm (off the chart, so not sure what actual level was)
    • Hardness: Couldn't get this test to work -- the agent kept separating, even after I took the tip from the kit's manual and added 5-6 drops of the hardness agent as the first step
    • Water temp: 84
  • Day 8:
    • Soda ash: the PoolMath app suggested i would need sixty-five lbs of soda ash to get the pool's pH up to 7.6. By contrast, the kit's manual's table (when extrapolated to 13 drops) suggested about 6.9lbs. I sprinkled in the 4lbs that I did have on hand, and agitated it around with the brush.
    • Shock: I couldn't get to a store for liquid chlorine today, and I had the 1lb bags of Clorox Shock XtraBlue+ that I had bought on day 5 already, so based on the PoolMath app's recommendation, I put in 2.5lbs of the sodium dichlor shock, and agitated it around with the brush. (I now realize this probably increased my CYA and did more harm than good as a result)
So, I have done exactly what you shouldn't do -- go to a pool store, throw a bunch of products in on a whim, use shock instead of liquid chlorine, etc. -- but I am hoping to get on track the right way.

Questions:
  1. Since I just don't have enough knowledge of our system to know how to correctly clean our filters, does that affect whether I should do a SLAM? Does the fact that I used NoPhos (which says to clean the filters after use) change the answer?
  2. Is there any way to measure CYA when it's just "above 100" on the test kit's scale?
  3. With high CYA levels, do I need to drain/exchange some water before doing a SLAM? How do you determine the right amount to drain off?
  4. Any idea how to solve for the hardness test not working? (The pink/magenta component separates into tiny droplets and it never turns blue)
  5. If I need to either clean the filters or drain the pool to lower the CYA level, then it will be at least a week before I have help to do that. What would I need to do during that week to keep the pool swimmable? It's going to be 104F here this weekend, so want to make sure we're ok to get in.
Apologies if I'm missing key info that would help answer the questions, and if the answer is just "call a pool service, you're in over your head", I wouldn't be offended to hear it!
 
Ok with the dilute test, CYA is at 160.
Also retested FC and CC:
FC: 8.6
CC: 0.8

Can you help me understand the urgency of draining? As I noted, I don’t think I can do that myself this weekend. In the meantime, the water is clear enough to see the bottom and there isn’t any visible algae. I’ve attached some pictures in response to my questions in the other thread, too.
 

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