Suggestions for how to treat algae bloom when I have to be at work

momof1tx · Feb 19, 2019

I'm pretty sure I have a mustard algae bloom that developed within the last 36 hours (noticed it yesterday afternoon but not the day before). My pool is all out of whack this winter due to rains, rains, and more rains, and the one tree in my neighbor's yard which deposits every single leaf and now blooming thingies into my pool. I have not stayed on top of chemicals, so the bloom is completely my fault.

Zero chlorine last night but no CC's, ph was 7.2, I forgot to test the TA, and it was after dark, so I didn't test CYA (but probably near zero). My salt cell is off due to cold water. I had a couple of gallons of bleach around the house so I dumped those in last night and brushed. (I couldn't make it to the store last night for more).

Bought lots of 10% chlorine today at lunch break and will run all tests (after I let the pool water warm up) and add this evening and brush brush and test again and I can get up earlier in order to have time to test and brush before I leave for work in the mornings. However, I cannot test every few hours because I work Mon-Friday. Any suggestions on tackling this beast? Come the weekend, I can watch it. It's cold and rainy here in East Texas, and rainy forecast through the weekend, but I'm prepared to work this as much as I can.

Texas Splash · Feb 19, 2019

Honestly, staying somewhat close is key, at least in the early parts of the SLAM to remove algae. The cold water "may" help you a bit this week in the sense that algae shouldn't multiply as fast, but it's still going to eat some chlorine. Followng the SLAM guidance to the letter is always best. Before you begin though, I would first do this: Add enough bleach to raise the FC to 10, verify it at 10, then test in about 10 minutes to make sure it's holding relatively well. If the FC completely disappears or dropped below 5, add bleach back to an FC of 10 and test again in 10 minutes. Repeat that until the FC holds THEN you can add stabilizer (if needed) for a CYA target of 30. From there - SLAM! The first couple days are the most critical to babysit.

momof1tx · Feb 19, 2019

Thank you for your reply! I'll get it on this evening and see if I can get ahead of it.

splashpad · Feb 19, 2019

@momof1tx It's not that it won't be successful, just that it will take little more time since the bump in FC will be less frequent

If you can add the FC often in the evenings (as soon as you get home) and then test & add frequently on the weekends, you'll have it back under control in short order!

momof1tx · Feb 20, 2019

So started SLAMing yesterday after running tests again. My CYA was not zero as I suspected (due to lots of rain this winter) -- it was 40-50, so I erred on side of 50 with CYA/Chlorine chart. I brought FC up to mustard shock level, but then it occurred to me, am I supposed to SLAM at shock or mustard shock level? I thought I read somewhere to SLAM until passes all 3 tests and then raise to mustard shock level for a couple of days.

FC held pretty level overnight last night but we had a day of sunshine, so it had dropped from 29 to 11 during the day. Brought it back up and it's been holding for the last few hours.

It's milky and I can't even see if anything is hanging on to the walls. Been brushing like crazy -- (fortunately, it was confined to the deep end of the pool when I first noticed the algae, but that probably doesn't make it any easier or quicker to clear).

My other question besides the appropriate shock level to use is do I concern myself at all with the pH level during this process, which could be a long process (week or more) from what I understand and from my understanding ph test is unreliable at high chlorine levels? ph was 7.2 and TA was 60 when I started SLAMing.

Thanks for the help!

momof1tx · Feb 20, 2019

Oh, another question: water is cold but should we brave it and try to see if we can get the pool light out so we can scrub around it as well as the returns and the booster connection?

Texas Splash · Feb 20, 2019

momof1tx said:
am I supposed to SLAM at shock or mustard shock level?

You'll want to maintain a regular SLAM level. Based on your CYA, an FC of 20 is perfect. We adjust the pH to about 7.2 before starting the SLAM, and yours was already good as well. As for the pool light, it would be a good idea if you can handle the chilly water to pull it. If not, see how well the SLAM goes for the next day or two. There may not be much growth behind it, or the cold water may keep it from growing right now and you can check it later. You'll know if the SLAM drags-on. Remember, the FC is expected to drop more during the day when trying to maintain an elevated SLAM than when maintaining a "regular" FC level. The additional FC at the higher (FC to CYA) ratio is more susceptible to the UV. But at night you hope to not lose anymore than 1 ppm of FC since there is not sun to fight. That's the OCLT, part 1 of the 3 SLAM criteria to pass. So keep maintaining the FC of 20 as best as you can with work and life interruptions along the way. Brush often and rinse the cartridge when the filter psi get to about 20-25% higher than at clean pressure. You'll get it.

ajw22 · Feb 20, 2019

Don’t worry about pH. pH test is not reliable when FC is over 10.

I wouldn’t tackle the pool light yet until the pool clears up more. If you cannot pass the Overnight Chlorine Loss Test then the light niche may be next. By then you may have warmer weather.