Is Black Algae sometimes not controllable?

[dobe12]

First - no test can measure a CH of 187 ppm. How did you get that?

Then, use Effects of Adding Chemicals, PoolMath

I filled container to 10ml. I added 10 drops 0010. Added 3 drops 0011L. Solution turned Red.

I then added 1 drop at a time of 0012. Somewhere between 7 and 8 drops it turned blue.

I multiplied 7.5 x 25 to get 187.5

Pool Math says it should be 450 and I should add 54 Lbs of Calcium Chloride.

Did I do it wrong?

 

[mknauss]

Nope, you used 8 drops so your CH is 200. No interpolating is needed.

I would suggest going to 300 ppm CH. Remember, the recommended values are a range. Poolmath simply picks mid range. Since you will have evaporation over the summer and will be adding fill water, your CH will rise some.

 

[dobe12]

I filled container to 10ml. I added 10 drops 0010. Added 3 drops 0011L. Solution turned Red.

I then added 1 drop at a time of 0012. Somewhere between 7 and 8 drops it turned blue.

I multiplied 7.5 x 25 to get 187.5

Pool Math says it should be 450 and I should add 54 Lbs of Calcium Chloride.

Did I do it wrong?

Nope, you used 8 drops so your CH is 200. No interpolating is needed.

I would suggest going to 300 ppm CH. Remember, the recommended values are a range. Poolmath simply picks mid range. Since you will have evaporation over the summer and will be adding fill water, your CH will rise some.

Ok, even at 200, Pool Math says to add 51 Lbs. Does it make sense to add 25 Lbs and check again in 2 weeks? Or should I add even less?

 

[mknauss]

Sure. Add 25 lbs and check it again in a week or so. Again, Poolmath is using the mid point of the recommended range. You can change that value to target. See Recommended Levels

 

[Katodude]

Do yourself a small favor. Test your calcium again. Calcium is very easy to add, and very hard to remove from a pool. Before you start adding double check.

 

[dobe12]

Do yourself a small favor. Test your calcium again. Calcium is very easy to add, and very hard to remove from a pool. Before you start adding double check.

I will double check! I haven't added any calcium yet.

Also I have a question about FC and CYA:

Why the difference in recommendations between Pool Swim U and TFP Pool Math?

Pool Swim U says the FC should be 3.0 if the CYA level is 50. Pool Math says the FC should be 5 if the CYA is 50. Why the significant difference in recommendations?

Thanks.

 

[dobe12]

Here's the PSU recommendation.

 

[Donldson]

Why the significant difference in recommendations?

What another source recommends is a matter for them to explain. We can tell you why we follow the FC/CYA Levels and how the ratios were initially conceived and honed over the years if you would like, but we can't tell you why anybody else chooses to recommend what they recommend.

 

[Bperry]

Here's the PSU recommendation.

Reference point: Your pool can use up ~3ppm of FC in a day of sunlight. Then you’re be left with almost no chlorine by the end of the day, bad stuff starts happening at that point.

 

[dobe12]

I've got almost all of the chemical levels where they should be. The one that's still off is TA at 130. I'm confused about the correct range for my pool.

The TFP "What are my ideal pool levels" says 60-80 is "ideal" but 80-90 is "acceptable".

The TFTestKits instructions say 100-120 is "Good".

Other sources say 80-120 is "recommended".

Mine is only 10 ppm off what most everyone else says is acceptable. Pool Math says lower PH to 7.0-7.2 and aerate to increase PH.

I've already spent time getting the PH to 7.6. What happens if I leave the PH at 7.6 and TA at 130?

Thank you!

 

[mknauss]

TA is the one parameter that can have a very wide range of acceptable levels. In reality, any level at or above 50 ppm is fine. You really just manage pH, keep it in the 7's, and the TA will do what it does.

TA - Further Reading

www.troublefreepool.com

PH TA Relationship - Further Reading

www.troublefreepool.com

 

[ajw22]

What happens if I leave the PH at 7.6 and TA at 130?

Nothing. All will be good. Keep your pH in the 7's.

 

[dobe12]

Thanks. Very helpful information, as usual!