Managing CH/CYA

[Rancho Cost-a-Lotta]

I am trying to manage my water chemistry to avoid calcium scaling and/or damage to my finish or equipment. I'm relatively new to TFPC. I know my CH and CYA are high, but my goal is to work with my current chemistry as far as I can take it. An algae bloom would probably push me to do a drain and refill since required shock levels would be astronomical. I understand the relationship between CYA and FC levels and have been maintaining my FC at 6 ppm and above. My pool gets full sun during the day. Water is clear (the best it has ever looked) with no signs of algae. I just ran an OCLT and passed. I plan to put my solar cover on this weekend, which may make things a bit more challenging.

Here is my most recent test.

FC - 7
CC - 0
pH- 7.4
TA - 90
CH - 750
CYA - 120
Borates - 40
Salt - 4000

It was suggested that I run my pH on the low side and work on lowering TA to 50-70. My current CSI is showing -0.26. Lowering TA and pH result in a lower CSI.

I've read that one way to lower TA is to bring pH down with MA and wait until is rises to 7.8 before adding more MA. My pool seems pretty happy around the 7.4 to 7.5. Should I add MA to bring it down to 7.2 now to reduce TA or aerate to a higher level first?

I'm looking for some input on fine tuning the numbers I have control of to mitigate potential damage.

Thanks,

Mike.

 

[Mr Bruce]

Your CSI is fine, that high CYA is going to make life tough. Are you on water restrictions?

 

[Rancho Cost-a-Lotta]

Thanks for the reply Mr. Bruce.

I am not on water restrictions and not concerned about the cost of the refill. My challenge is disposal of the waste water. I'm on septic and the city won't allow the disposal of salt water through the storm drains. I can drain onto my own land, but not sure how 10,000 gallons or so will look on a 1 1/4 acre lot (horse property). I'm afraid my downhill neighbor might get flooded out. I may need to do some research on haulaway of waste water unless someone has some suggestions.

Can you describe what my biggest challenges will be with the CYA level?

Update...

I looked at the city website again. It looks like draining into the storm drain is OK. I'm a bit concerned about the effect of the runoff onto my neighbors property.

 

[tim5055]

Can you describe what my biggest challenges will be with the CYA level?

Keeping algae away and being able to test pH.

I took over my pool with a CYA of about 250 (CYA tests above 100 are just a guess, not very specific contrary to what anyone says). With a CYA of 250 I had to keep my chlorine level at around 20 just to keep algae away.

In your case, your absolute minimum FC you should have is 9 (which by your admission above you are below). To keep it at 9 you need to target 12 - 14. So, the pH test does not work properly above FC 10, to test pH you will have to allow FC to get critically close to your minimum. See the problem....

 

[Mr Bruce]

It will be difficult to maintain the FC level you will need to be at. FC of 6 will be the minimum, drop below that and it's asking for trouble.

I understand about the draining problem. Even if you could manage 500-1000 once a week it would help. Obviously I'd speak with the neighbor to see if there were strong objections.

edit: I defer to Tim's target number. 120 CYA is literally not on the chart and I was trying to calculate it manually, probably wrong.

 

[Rancho Cost-a-Lotta]

Tim,

You said,

So, the pH test does not work properly below FC 10, to test pH you will have to allow FC to get critically close to your minimum

Do you mean above? If so, I think I understand.

Any area of ever increasing confusion: Pool math shows by recommended FC levels as 6 minimum and 9 target for SWG. Should I be aiming higher?

Thanks again!

 

[tim5055]

Tim,

You said,



Do you mean above? If so, I think I understand.

Any area of ever increasing confusion: Pool math shows by recommended FC levels as 6 minimum and 9 target for SWG. Should I be aiming higher?

Thanks again!

Yea, I'll fix it - above. And - Bruce is right. As you are a SWCG pool your minimum is 6, your target goes up into the 8- 10 range.

Were it my pool (based on your update above about using the storm drain) I would at least do a partial drain until you got to a point eh CYA test works natively. 80-90 would be good. Then slowly work down to where you want from there.

 

[Rancho Cost-a-Lotta]

Perfect. Thank you.