Refilling now - next steps?

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#1
Just turned on the hoses to refill my pool after draining about 80 - 85% of the water to deal with high CYA and CH, and also to attack some stains while I had things drained.

My question is, should I hit the pool with some chlorine now, while it is just starting to fill, or wait a bit ('til morning) then test and add some then?

Any advice?

For what it's worth, the water when I started draining:

FC 13.5
CC 0
pH 7.4 (tested using 1:1 dilution with distilled water due to high FC - I know this is approximate)
TA 110
CH 450
CYA 150 (tested using 1:1 dilution with distilled water - many tests - this is the average)
Temp 79

I did some testing of my fill (tap) water a few days ago in preparation for this. I had some trouble with FC - maybe it's because of what they use to chlorinate here in FL?

Anyway, here's what I got:

FC 1.2
CC 1
pH 8
TA 200
CH 210

I think I drained about 85 - 90% of my pool water (total volume = 12000 gal) , so just using some ratios, I expect I would end up with the following once it's refilled:
FC 3.3 (not sure about this or CC due to uncertainty around my tap water measurements)
CC 0.9
pH 7.9
TA 187
CH 245
CYA 21.3

Any thoughts here on whether I need to add chlorine right away? Amazingly it looks like I'll need to add some CYA and I know I'll have a battle on my hands to reduce TA and get the pH in check. Any pointers or advice much appreciated!
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#2
I looked through your post history and I didn't see that you're battling algae. If not, don't mess around adding any chlorine while it's filling. Just fill it up and get it circulating and mixed, then retest. If you mis-guessed and drive FC too high, it will affect the pH test. You can help the mixing by brushing some. If you have a wall whale brush, that really gets the water moving side-to side.

Post accurate results and we can help you, if you can't figure it out yourself. It's looking like you have a handle on the chemistry already. Just don;t get all OCD about it.
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#3
You're right, no algae battles. This drain refill was mainly to deal with CYA and CH. I'll get some measurements in the morning and see where things are sitting. Thanks for the input! Oh - and it will be a real struggle for me not to be OCD about the chemistry! Haha! I'm wired that way!
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#4
Refill almost done. About a foot to go. Started circulating water through filter via main drain line once returns were submerged. Sampled after about 45 mins of that.

FC 3.5
CC 0
pH 8 (maybe higher, basically super red - expected based on sampling fill water earlier this week)
TA 220
CH 225

Couldn't test CYA this morning - out of reagent - will get some at lunch time and post result soon. Basically I am confident that CYA will be around 30, maybe less, just based on how much volume I replaced.

SO - I know that at CYA 30 I would need to maintain minimum 2.25, target 3.5 FC. I'm thinking to add some chlorine soon, just to be safe in first days here at new lower FC level. May add enough to get to 7 just to see how the pool sits with new water, etc.

BUT - since pH is so high, maybe I should address that first with some acid, shoot for 7.5 or 7.4? Not sure how easy this will be given sky-high alkalinity (thanks again to fill water).

Any advice or thoughts appreciated!

A couple of quick notes: FC test was kind of wierd. 10 mL sample barely turned pink with 2 scoops of powder. For first couple of titrating drops, sample briefly cleared, then turned darker red and stayed there. On about drop #4, sample began to gradually clear and then was completely clear and stayed clear after drop 7. Never seen this before, maybe due to chloramines in city water?

Also, pool water has a green/blue tint this morning that I haven't seen before. Not cloudy, really, just blue-green-ish. Usually it's been crystal clear. Maybe a bi-product of me scrubbing walls when pool was emptied yesterday...
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,330
San Dimas, CA (LA County)
#5
Adjust pH with acid before adding bleach. With that high TA, target 7.2. It'll pop back up fast. Let the water circulate half an hour or so before adding bleach, or accelerate the mixing by brushing.

Greenish tint could be trace amounts of Iron. The rust is a pale orange but when combined with the normal blue, can look green. It can get worse when you initially add bleach, but usually goes away in a day. High pH also makes it worse.
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#6
Awesome advice - thanks. I'm going to add some acid now. PoolMath says 69 oz so I'll trickle that in and then wait a bit before any bleach. Meanwile I'm off to pick up some CYA reagent during acid circulation.
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#7
OK - just retested chlorine and pH after acid addition about 90 mins ago. No chlorine added yet. Refill is now complete - back to normal operating water level.

FC 3
CC 0
pH 7.1
CYA <30
Temp 80

Tested CYA and basically black dot is totally visible even at top of test cylinder, so something less than 30 ppm. Not surprising since I ended up draining a lot more of the pool water than I originally intended (this to uncover some stains on the pool floor and get after them a bit). I would guess something like 95% of my water is now tap water, so I'm likely sitting somewhere around 8 ppm CYA.

So, I know I'll have to add some stabilizer - ironic since high CYA is really why I drained the pool in the first place! Haha! But - most of my ugly staining is GONE, so it was worth it to drain a little extra.

For now, I may use something like 6 ppm as my FC target, just in case I have crazy solar losses due to low CYA. After things settle down a bit, maybe in a day or two, I'll shoot to add back some CYA. Meantime I'll watch the pH and try to hold it a bit low, just to start pecking away at the high TA.

Any thoughts on this plan, or other suggestions? I'm all ears - never done this before!
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#8
Another thought - I have a whole tub of trichlor tabs in the garage, inherited from the prior homeowner. That tub, I'm sure, was the root cause of the elevated CYA in the pool - I think prior owner was a puck junkie.

I guess I could throw a few of those in - might keep FC steady while adding some CYA at the same time - I could pull 'em out when levels got high enough, but maybe that would take too long. I've been keeping the pucks around to use during brief periods where I'm out of town...
 
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sfbayjay

sfbayjay

Active member
Mar 8, 2017
44
Largo, Florida
#9
Greenish tint could be trace amounts of Iron. The rust is a pale orange but when combined with the normal blue, can look green. It can get worse when you initially add bleach, but usually goes away in a day. High pH also makes it worse.

Richard310: could you take a look at my new post here: Iron Stains (I think) Removed - Sequestrant Needed Now? related to iron in the water and my efforts to remove stains yesterday? I fear that maybe much of the iron I scrubbed off the walls remained in the small amount of water left in the bottom of the pool before I started refilling and now I may just re-deposit it all.

Can you offer any insights or advice? I don't want to go through all of that work (or expense) again! Haha!