Quick question: DiChlor shock as FC boost

[MichaelT20]

Hi all,

Been following tfp principles and as a result never really needing the DiChlor shock (Leslie’s ChlorBrite) I was given early on when my pool opened.

I just added some calcium hardness to my pool and am expecting my fc to drop (it has the last few times I’ve done this).

In addition - My cya is a little on the lower end for my swg (it’s 50).

With the above in mind am I ok to throw a bag of DiChlor into my pool *if* needed (fc test comes back Low in a few hours). I’ll be using my dpd drop test to confirm fc loss before adding.

1 lb will raise fc by 3 per pool math.

If I do - I assume there’s no reason we can’t swim come morning? The whole “wait 12-24 hours after shocking” rule is more so if you raise your fc like crazy - not about using “shock”.

Am I understanding this all correctly ?

I plan to let my swg run overnight as well to get me back into the 5-6 range that I’ve been aiming for.

Tldr - can I use a single bag of DiChlor for a quick fc boost considering my cya is a bit on the low end anyway ? Waste not want not

 

[revitup]

So your FC crashes with the addition of calcium chloride?

 

[MichaelT20]

It has in the past. I’ll let you know in about an hour if it did again

 

[MichaelT20]

Tonight I tested FC at 7:45pm. It was at 5.0 (10ml sample - 10 drops). CC was at 0.
I added 8lbs of Leslie's Hardness Plus
I just tested again, 9:15pm -- 30 minutes later -- FC is at 2.5 (10ml sample - 5 drops). CC is at 0.5 (or less, since i used the 10ml sample size).
I'll test again in another 90 minutes.

So back to the topic at hand -- I'm cool to use 'Dichlor shock' to boost my FC as long as my CYA is a little low too - right? Theres no harm in just treating Dichlor as Chlorine+CYA in one, assuming I follow the PoolMath estimates?

 

[Newdude]

If I do - I assume there’s no reason we can’t swim come morning? The whole “wait 12-24 hours after shocking” rule is more so if you raise your fc like crazy - not about using “shock”.

That is pool store 'dump and pray'. They don't know where you are, or what the addition will do to you, so they tell you to stay out.

At TFP, you know exactly where you started and exactly where you will land. Because you understand the relationship of CYA and FC, you know that swimming is safe between minimum and SLAM (40%) of any CYA level.

The powdered shocks and pucks are fine if your CYA / CH have some wiggle room. Boy, it sure is NICE knowing what's going on and what everything will do, huh ?

 

[Mdragger88]

Tonight I tested FC at 7:45pm. It was at 5.0 (10ml sample - 10 drops). CC was at 0.
I added 8lbs of Leslie's Hardness Plus
I just tested again, 9:15pm -- 30 minutes later -- FC is at 2.5 (10ml sample - 5 drops). CC is at 0.5 (or less, since i used the 10ml sample size).
I'll test again in another 90 minutes.

So back to the topic at hand -- I'm cool to use 'Dichlor shock' to boost my FC as long as my CYA is a little low too - right? Theres no harm in just treating Dichlor as Chlorine+CYA in one, assuming I follow the PoolMath estimates?

Be aware of its acidic effects as well - looks like it will drop ph by .1 or so.

Dichlor & trichlor are ok to use So long as u know what it will do & are aware of it’s effects on all your parameters.

 

[MichaelT20]

Thank you both .

The powdered shocks and pucks are fine of your CYA / CH have some wiggle room. Boy, it sure is NICE knowing what's going on and what everything will do, huh ?

It really is great !! Im still a newbie (only had this pool for 2 months - it’s brand new) so I’m in the “validating my research” phase - thank you for confirming !!

Be aware of its acidic effects as well - looks like it will drop ph by .1 or so.

Yup - not too worried here my swg is bumping my ph daily. This’ll save me a few drops of muriatic this week

 

[PoolStored]

my swg is bumping my ph daily. This’ll save me a few drops of muriatic this week

SWCG causes a miniscule pH impact. Your TA, plaster if it is new, and any water features you might are likely the drivers of pH rise.

 

[Newdude]

Your TA and any water features you might are likely the drivers of pH rise.

And don't forget running the pump 12+ hours for the SWG to produce enough chlorine. The SWG always takes the blame but the dang sneaky pump is sitting there snickering the whole time. He would have gotten away with it too if it wasn't for you meddling kids !!!

 

[PoolStored]

And don't forget running the pump 12+ hours for the SWG to produce enough chlorine. The SWG always takes the blame but the dang sneaky pump is sitting there snickering the whole time. He would have gotten away with it too if it wasn't for you meddling kids !!!

Yeah, I forgot swimming.

 

[MichaelT20]

SWCG causes a miniscule pH impact. Your TA, plaster if it is new, and any water features you might are likely the drivers of pH rise.

Oh yes - definitely true. The plaster is only 2 months old and we have a spillway from the hot tub - small but enough that there’s constant airation.

I want to give borates a try - thinking when we open the pool next year I’ll give it a go. I’m still getting the hang of the “essential” chemicals - so don’t wanna add too many new variables just yet.

 

[MichaelT20]

P.S - my fc did drop as expected. 2.5 ppm from 5 to 2.5. I just tested again - still 2.5fc and 0.5 cc.

I added my 1lb of DiChlor just now. Turned off the swg just to be safe. Will test again in 90 minutes then probably let the pump run overnight to be safe and re-enable the swg in the morning

 

[PoolStored]

Oh yes - definitely true. The plaster is only 2 months old and we have a spillway from the hot tub - small but enough that there’s constant airation.

I want to give borates a try - thinking when we open the pool next year I’ll give it a go. I’m still getting the hang of the “essential” chemicals - so don’t wanna add too many new variables just yet.

Given our experience here, I would wait until the season after next to go to borates. At least wait until your water chemistry is stable. Borates are not magical and they do add to the complexity of your water chemistry. You can still lower TA with borates in the water and borates do not change the fact that you'll still use the same amount of acid. You'll just be adding more acid with less frequency so the total acid volume used is the same.

 

[MichaelT20]

Ok gotcha that sounds good. Thank you . I’ll definitely hold off a bit.

 

[Newdude]

So, a bit if unsolicited advice. I just built my 2nd pool and had to dial in a new SWG. The old pool had tons of shade and this one is zero shade ever. I dialed it in at 10FC for lots of wiggle room. Once I proved I had it set right and it could maintain 5FC, I left it maintaining 10.

10+ FC invalidates the PH test, so I test in the evenings as it's usually dropped to a 9 before it picks up FC overnight.

We have short seasons in the Northeast and don't have the longevity concerns of the folks in the hot climates with 10 month seasons. Use that SWG like you're putting it away for 6 months each year.

 

[mgtfp]

Really appreciate your thorough approach in documenting this calcium increaser issue, and that you took the effort to wait until sunset to rule out UV and/or low CYA as the the culprit.

 

[MichaelT20]

Thanks More details on that are on this thread, I have more thorough notes there: Can adding a lot of calcium chloride at once reduce FC??