Question about new pool & CA

[smontoto]

Pool w/diamond brite was filled Dec 19th so the plaster is approx 4 months old. Everything looks crystal clear and keeping an eye on the PH and adding acid every day or two. The question I have is about the calcium hardness, should I add a little to bring it in range? Or leave it alone right now since it’s new?

Yesterday’s test results
FC 3.8
CC 0
PH 8.0 (I am trying to keep it at 7.8 but is 8 or a little higher every time I test which is almost every day)
TA 70
CH 310
CYA 70
SALT 2800
TEMP 72

CH Has been between 300-340ish since I began testing in January

Anyway just wanting to clear up my confusion since it’s a new pool and lowish CH. At what point do I add calcium.

Thanks

 

[PoolGate]

HUH? Your CH is fine it is within range.

 

[smontoto]

The TFP guidelines say between 350--450 for a plaster pool with SWG. Am I confused?

 

[PoolGate]

It's close enough.

 

[smontoto]

Ok thank you, I don't know much about pool chemicals so I will take your word for it. I am a pretty precise guy so when I see values I try to stick to them.

Do the rest of the chemical ranges have some "extra latitude" in them as well?

 

[Rancho Cost-a-Lotta]

Your Ch is fine now. As water leaves your pool through evaporation, the calcium remains. Depending on the Ch content of your fill water, you'll be adding calcium every time you top off your pool. You may want to test your fill water to see what you're up against. Try to maintain your Calcium Saturation Index (CSI) within range and preferably on the slightly negative side (-0.1 to -0.3) to avoid calcium scaling. You can calculate your CSI using the Pool Math app or web page. I ran your numbers with a pH of 8.0 and you're at -0.01 right now. If you keep your pH between 7.8 and 8.0, your CSI will be within perfect range. As water temps increase, you may need to drop your pH down a bit. Links for CSI and Pool Math are in my sig. Your chemistry looks real good from where I'm sitting.

 

[smontoto]

Ok, thank you both! Just trying to get a grip on proper adjustment technique and balance. So it's not necessarily precise chemical ranges, it's the CSI that is most important. Correct?

 

[Rancho Cost-a-Lotta]

In your case, correct. As PG mentioned, your CH is close enough. You can counteract the lower CH with proper pH balance.

 

[duraleigh]

The suggestion of CH between 350 and 450 for SWG's is mildly erroneous and needs revision. I believe it got introduced as a result of chasing the CSI holy grail. (can you tell I am not a fan of csi......it's too often misunderstood)

Suggested CH is inconsistent on the forum but it has never been disproved that 250-400 is not the best range......that means you are just fine where you are.

There is certainly a VERY wide range that one can manage CH (some owners report 1000 ppm but they are REALLY good managers) but the 250-400 has always seemed to work.

Additionally, CH almost never leaves a pool. As a result, CH in most all pools will increase slowly with time.......the speed depends on how much CH is in your fill water. I doubt if you have much in Louisiana

Do the rest of the chemical ranges have some "extra latitude" in them as well?

Sort of. There is no range where the upper/lower limits are "go/ no go". Your arms and legs usually don't fall off when you stray a little outside these parameters but they are guidelines that are proven to work over and over by thousands of pool owners and we should all intend to operate within them.