PH / Chlorine Question

Jump to latest Follow Reply
J

Jfish303

Active member
Jun 4, 2020
35
Denver, CO
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-30
I am in Denver CO and have a 15,000 gallon fiberglass pool that was open all winter. I have an auto cover. My chlorine is around 2-4 range with the SWG at 8-15% output (3200ppm salt) and my ph is usually around 7.6. Occasionally it will go to 7.8 and a cup or so of acid will bring it back down.

Recently after a bunch of rain my ph went to 7 and chlorine to almost 0. I bumped up the SWG to 50% and added 2 cups backing soda. Neither had much impact. Eventually I added more backing soda to get to 7.3 (with more rain) and added bleach to get the chlorine to 3.

It seems the SWG is not making the impact it should and same for the backing soda which should have raised the ph much higher.

Any thoughts / help on what might be going would be appreciated.
 
Baking soda will increase the TA but not pH directly. Your FC crash may be to the start of algae. SWGs are not designed to increase FC in large amounts, only maintain a good level. I would add about 6-7 ppm of liquid chlorine ASAP then conduct an Overnight Chlorine Loss Test to see if algae is a concern.
 
  • Like
Reactions: Bperry
Jfish303 said:
FC is 3.6 and CC is .8-1 which I think should be near 0 based on what I read. So maybe shocking would be a good idea?
Click to expand...
Seeing that your FC fell close to zero in the recent past, I would still do as noted above in Pot 2 to increase the FC to about 6-7 pm and perform that Overnight Chlorine Loss Test. If algae already started, your SWG will never sustain the FC for you, so it's important to be sure. That in itself could resolve the slightly elevated CC issue.
 
I added more bleach and will let the circulate and then make sure I am in the range for the test. Hopefully just adding the bleach to get to 6-7 will resolve the problem as the water does look fairly clear.

It does seem like SWG is struggling to maintain chlorine at the moment so that with the elevated CC made me think that algae had already started
 
Switch to 10ml testing for FC/CC and you'll save 2.5x the R-0871. The number after the decimal never changed the price of beer, although it's needed to get to the next full number.

A 2.2 and a 2.5 both equally suck. A 9.0 or a 9.2 are both golden. (For most CYA levels)
 
Cover on 100% of the time? If not - what's your CYA? Perhaps it's fallen and not protecting the FC the SWCG is producing.
A full set of test results and a complete signature would really help.
 
Jfish303 said:
Get FC to 9? Not 6-7 as indicated above. No problem switching to 10ml test
Click to expand...
@Newdude 's point was that 2.2 or 2.5 were below minimums. 9.0, 9.2 or 7.2 or 7.0, the difference in the test results between .2 and .5 discrimination doesn't matter you know you are in a good range and the .2 discrimination of the 25ml test is a waste of reagent.
 
  • Like
Reactions: Newdude

Enjoying this content?

Support TFP with a donation.

Give Support
I understood about the test. Was just wondering if the target range was 6-7 or something higher like 9.

The cover is on almost 100% of the time. We have no used the pool that much as it won't stop raining

I will do a full test of all chemical later tonight
 
Jfish303 said:
Was just wondering if the target range was 6-7 or something higher like 9.
Click to expand...
I recommended the 6-7 range because the OCLT instructions simply say "at least 3 ppm or above". Problem with that is that if you do have algae and started the OCLT with an FC of 3 or 4, it could all disappear very fast. So while I recommended 6-7, if you elected to go a little higher that's fine as well. Especially since your FC was a bit low before, the water could use the extra help.
 
  • Like
Reactions: Newdude
Okay turned off SWG last night and just let the pump run.

Measurements last night were 6.5FC (13 drops using 10ml sample) and maybe .5CC (it barley turned pink with addition of reagent to see if CC was present but did clear with addition of 0871)

Measurements this morning were 6.5FC (13 drops using 10ml sample)and maybe .5CC (it barley turned pink with addition of reagent to see if CC was present but did clear with addition of 0871)

PH measured 7.8

I will turn on the SWG and see if things start behaving normally and continue testing unless there is advice to do something more.

It's hard to convey through a keyboard but I really appreciate all the help
 
Last edited:
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply