Algae but no CC

[mknauss]

pH and CC cause skin conditions. FC below SLAM level rarely presents a problem as the active chlorine level is less than tap water.

 

[Blue Horse]

Good to know.

Back to rising ph, if i start slamming now with TA=120, should I add a fixed amount of MA daily during the process? No PH test, but in anticipation PH would rise otherwise.

 

[mknauss]

No. Deal with pH after the slam is over.

 

[Blue Horse]

mknauss, can you double check "FC below SLAM level rarely presents a problem as the active chlorine level is less than tap water"?

It looks tap water's chlorine level is up to 4ppm only?

 

[mknauss]

Correct -- that is 4 ppm with 0 CYA. A FC at SLAM level for the CYA has a fraction of the active chlorine.
See Science of "safe to swim up to SLAM level" and Pool Water Chemistry

 

[Blue Horse]

ah... hard to beat you guys... ;-)

Before I slam the pool, if OCLT shows less than 1ppm loss, is there still a good reason to to the slam anyways? I changed 60% of the pool water, PH at 7.4 now, and SWG has maintained FC between 4~6ppm in last 4 days. I still get a bit algae, but much less and can be easily scrubbed off the surface. Water is clear.

Thanks!

 

[aeh0603]

If you see algae, then it's time to SLAM.

For the purposes of the SLAM criteria, clear water means both transparent (can read heads or tails of a coin in the deep end) AND no visible algae. If you see algae, you have failed the "clear water" test.

 

[Blue Horse]

As I start to slam, can I keep the SWG on to provide extra stability/buffer to FC level? I will only turn it off late afternoon when I start the OCLT.

Does adding muriatic acid also reduce calcium hardness of the water? My test today is posted below. The calcium level was 225ppm 2 weeks ago. I have been adding muriatic acid every 2~3 days in keep PH at 7.2~7.5 level (from 8.2+ before). TA has come down from 140 to 120 (I have a waterfall). I am concerned calcium gets too low before PH and TA get to the appropriate level.

4 Free Chlorine
No Combined Chlorine
175 ppm calcium
120 Total Alkalinity
20 CYA
5 10 Cl Br
PH 7.5

 

[mknauss]

We do not recommend using the SWCG as it provides a very minor amount of FC versus what is needed for SLAM levels. But up to you.

CH is only reduced by removing the water from the pool and replacing with lower CH water. No chemicals added can lower CH levels.

 

[Blue Horse]

18 hours into slam. At CYA=30, FC requirment is 12 but I raised fc to 15 instead to make sure. When it is time to dial up for mustard algae, I plan to go 3-5ppm extra buffer as well. Hope no issue in this plan?
should I throw all nets, brushes, toys into the pool to kill possible algae on these items?

I will scrub the skimmer surfaces. Not sure how much effort I need to put in to scrub the cleaner, which have lots of hard to reach surfaces?

 

[mknauss]

Waste of chlorine to go above SLAM level FC. Can also harm pool surfaces. Raise FC to SLAM level as often during the day as possible, not less than 3 times per day.

 

[Blue Horse]

Between 8pm last night and 8am this morning, my pool lost 2ppm FC. Water was crystal clean at both time. And I washed the cartridge filters two days before.

I am starting to wonder maybe 8am test was too late? It was cloudy when I did the test.

 

[mknauss]

This time of year, the morning test needs to be about 6 am. But I doubt you would have passed anyway with a 2 ppm FC loss.

Stay at it.

 

[Blue Horse]

Don't think I will ever get up that early, any time of the year ;-)

If I test at 7~7:30am in the morning, would you say I'd pass with 1ppm FC loss (compared to 8pm tonight's FC level)?

I kept the vsp at low rpm (1,500) overnight, instead of the 2,500rpm during the day. Wonder if that has any impact?

 

[mknauss]

Pump rpm is fine. Why do you need the high rpm?

Do the test as early as you can.

 

[Blue Horse]

My other hobby is reef fish tank, where in most cases high flow helps with water filtration. What will be a good rpm to run the pool during the day?

The other reason: My vsp speed for solar heating is set at 2,400 rpm (any rpm below 1,900 here will cause flow problem). During the day, if I run the vsp at 1,500 rpm only, when the solar heating switches on and off I could hear air bubbles in the pressure side, making their way to the pool. Running vsp at higher speed minimize that transition period.

By the way, is this normal to have that many air bubbles and noise on the pressure side?

I may have a little air leak on the suction side, as occasionally there will be ~1 cubic inch of air bubble swirling right in front of the filter pump housing. Don't think that leads to air in the pressure side though.

 

[mknauss]

Low flow helps with filtration in a pool filter.

Any air in your system means you have a suction side air leak.

 

[Blue Horse]

I will open another thread to discuss air in the filter housing and solar plumbing.

I tested at 6am this morning, at different spots of the pool the FC reading varied by as much as 1.5 ppm. It was during a window of 10~15 min. The pool pump has been running overnight at 1500rpm.

Scratching my head. I guess the most likely cause could be I tilted the bottle at different angle (could be 30 degrees difference between tests), and/or the speed between drops were different.

The other possibility is the volume of power. I made sure the power is flush with the spoon, but there could be different amount of power stuck to the inner surface of the spoon.

Love to hear/read suggestions to produce consistent result.

 

[Mdragger88]

I just always test at the same spot - the area with the worst circulation - so i know my fc is good everywhere else if its ok in that spot

 

[Blue Horse]

Tested 6am this morning - major achievement (early bird)

OCLT (between 8pm to 6am) is 0 ppm, and cc 0~0.25ppm. Moved onto elevated FC level starting 8:30am to kill possible mustard algae. Plan to stop adding chlorine by noon tomorrow.

Confirmed that different spots in my pool has FC level that vary as much as 1~1.5ppm. Surprising and good to know.