FC dropping fast, TA rising

[agonista]

Are you saying TFP has a correlation between FC loss and high TA, or some other forum?

iirc, i cannot post links, so see the further reading sections of wiki for PH TA relationship and TA. this all references information here on TFP.

what these sections and several related threads - which i also cannot link to - suggest is that high TA leads to rapidly rising pH, e.g. post MA addition. other threads show that FC loss increases substantially as pH increases to 8.0 and above. this means that if you don't keep your pH under control, which is modulated by TA level, it leads to high FC loss. adding MA every 24 hrs is not a very pleasant scenario, particularly because i have unpredictable wind direction and intensity near my pool, which forces me to use full face ppe to avoid burning my nose with MA fumes - even when i use the technique to minimize pour height.

 

[ajw22]

Are you saying TFP has a correlation between FC loss and high TA, or some other forum?

I don’t question what works for a person.

 

[agonista]

the impression i get after reading a bunch of threads on this topic is that not everyone needs to drop TA to this target range (60-80) for a plaster pool to get pH stability.

to get any level of pH stability, i've had to drop TA to 60. i might go to 50 if pH doesn't stabilize at 60.

 

[agonista]

ugh.

i am still seeing high FC loss rate, 4.5 ppm today, and i don't know what could be causing it besides algae. oclt is consistently 0.5 ppm, suggesting that algae is not the cause of the FC loss.

my levels this morning were FC 7.0, pH 8.0, TA 50, CH 230, CYA 50, and by this evening i had FC 2.5, pH 7.7.

while i was lowering TA from 170 to 50, i had several days where FC loss was only 1-2 ppm in full sun. i suspect that my pH may be driving the high FC loss rate, but i cannot keep the FC low by adding MA because my TA is already as low as it can get for a plaster pool.

could it make sense to add borates to buffer/stabilize pH, where this could reduce FC loss rate?

i only took over maintenance on this pool last year around july, and i never had an issue with FC loss being this high prior to the past several weeks.

 

[Newdude]

my levels this morning

Like 8 AM or 12PM ? CYA needs overhead sun for best results. That'd be my 1st suspect for high loss with none overnight.

Lord knows the test laughs at all of us, so it's not unreasonable that you could be a little off. Or. The blazing FL sun is taking its toll and 10 more CYA may help.

the impression i get after reading a bunch of threads on this topic is that not everyone needs to drop TA to this target range (60-80) for a plaster pool to get pH stability.

Correct. With regular Ph management, TA usually settles itself and no two pools behave the same.

Is the pool new from last July? New plaster can cause Ph rise for a year.

Do you have water features or a spillover ? Running those jacks the Ph. We recommend flushing them twice a day for 15 mins then leaving them off when not out there enjoying them. No need for them to hurt if nobody is enjoying them.

could it make sense to add borates to buffer/stabilize pH,

Yes it could. When it helps, you typically need doses half as often, but twice as much per dose. It's the same in the end except for the frequency.

where this could reduce FC loss rate?

Nowhere that I'm aware of. If you saw the loss dip it would likely be coincidence.

i only took over maintenance on this pool last year around july, and i never had an issue with FC loss being this high prior to the past several weeks.

Again, the UV index is crazy in many places already, and yours is crazy compared to everyone else's crazy. They're telling me to brace myself this week and it's like March by you.

 

[agonista]

Like 8 AM or 12PM ? CYA needs overhead sun for best results. That'd be my 1st suspect for high loss with none overnight.

morning measurements at 0645, evening measurements at 1900. CYA has been steady at 50 for weeks, but i'm reticent to add more in case i need to SLAM.

Is the pool new from last July? New plaster can cause Ph rise for a year.

this pool is in need of a retiling (~5% of tiles have fallen off) and overall update. it is roughly 15 years old, but i took over maintenance only last july after i had 2 incompetent pool maintainers in a row.

i have wondered if this could be related to the problems i've been seeing - some kind of interaction between old plaster behind tiles and water chemistry. i suggest this because despite it being very hot here, i never saw this level of FC loss last summer, which had very similar weather.

Do you have water features or a spillover ? Running those jacks the Ph. We recommend flushing them twice a day for 15 mins then leaving them off when not out there enjoying them. No need for them to hurt if nobody is enjoying them.

i have a fountain that is plumbed in parallel with the pool returns, and there is a spillover from the spa into the pool. there are returns in both the spa and the pool, so i require some amount of spillover flow to ensure mixing in the spa. i think i can dial down the flow to the spa return and reduce the overall run time of my vs filter pump, i will try this out tomorrow morning.

Yes it could. When it helps, you typically need doses half as often, but twice as much per dose. It's the same in the end except for the frequency.

ah, Dang. i'm not sure that is going to help then.

Again, the UV index is crazy in many places already, and yours is crazy compared to everyone else's crazy. They're telling me to brace myself this week and it's like March by you.

it has been really hot here lately, about 90-100 F before any humidity factored in. until several days ago, there was almost zero rain and full sun every day

 

[Newdude]

but i'm reticent to add more in case i need to SLAM.

You have recent passed OCLTs. Pass another if it helps you feel better. Then stay free and clear from min at the low FC point in the day and you'll have no algae.

think i can dial down the flow to the spa return and reduce the overall run time of my vs filter pump,

Flush the spa twice a day (15 mins) when not in use. (And the fountain if possible to seperate from regular return)

i'm not sure that is going to help then.

Half as often is still nice.

morning measurements at 0645, evening measurements at 1900. CYA has been steady at 50 for weeks,

Get a lunchtime CYA test on your next day off. But regardless of what it says, the FC loss says it's a bit low.

 

[agonista]

Get a lunchtime CYA test on your next day off. But regardless of what it says, the FC loss says it's a bit low.

tested CYA today, and sure enough, it was way low - under 30. i had CYA at 50 only a few weeks ago and got the same measurement several times over a longer period, so i'm pretty confident i'm experiencing substantial CYA degradation due to water temperature, which is routinely over 90 F the past several weeks.

i was under the (mistaken) impression that rapid reduction of CYA could only occur by pumping out water or microorganisms that aren't relevant here in FL. i definitely missed the note at the bottom of the CYA further reading section about accelerated CYA loss from oxidation with water temps over 90 F.

time to bring CYA back to 50-60.

 

[Newdude]

tested CYA today, and sure enough, it was way low - under 30. i had CYA at 50 only a few weeks ago and got the same measurement several times over a longer period, so i'm pretty confident i'm experiencing substantial CYA degradation

Mine got away from me the same exact way month or two ago. Lalalalalalalalalala fine lalalalalalalaala *record scratch* excess FC loss.