Very high calcium!

Chismoso56

New member
Jul 21, 2019
2
Scottsdale, az
Hi everybody,

Amazing forum and website- I'm glad I found it! New poolowner here in Arizona. Our 30,000 gallon pool has been maintained by the prior owner's "pool guy" for the last couple months (and who knows how long before that) while we settled in. I received a TF100 test kit, and found the following:

Daily reader:
Chlorine: 5 (max)
pH: 7.5

Levels:
Chlorine: 13.5 ppm (26 drops for free chlorine, 1 drop for combined chloramines)
Calcium: 3250 (150 drops, and the color never turned blue; turned clear at ~130 drops - I think it was a volume dilution issue, given the massive amount needed. So I diluted the pool water 1:10 with reverse osmosis water and repeated it - still needed 13 drops to turn blue)
Alk: 210
CYA: 500 (it turned cloudy almost immediately. So I diluted the mixed sample 1:5, and then it's cloudy at the 100 mark - not sure how accurate this is, and if the high calcium causes precipitate issues).

Our pool guy has been just throwing in Costco shock into the pool whenever he seems to feel like it, about weekly. Many times, he doesn't even seem to check the pool chemistries. There's a ton of calcium built up on the sides of the pool (that even with scrubbing, starts to come back thinly within a week). Understandably, I'm interested in learning more from you great folks at TFP and start managing my own pool!

From Pool Math, it says I pretty much need to drain my pool (93% volume). However, we have a plaster pool with some sort of pebble finish, and it's around 110-115F (43-46C) outside in Phoenix, which would likely be very bad. Given the ridiculously high level, I don't think slow cycling the water will likely be sufficient either. Plus, the free chlorine calculator doesn't seem to work really well when the CYA is reading at 500 - it seems to target free chlorine 38-51, and I'm not sure the CYA level is correct in the first place. Currently, I'm thinking of just maintaining the chlorine (maybe eyeball to 5+ on the K1000) and pH 7.2-7.8 until actual draining this winter, but I'm open to hear any thoughts!

In good news, the pool looks clear without algae at least. Thank you in advance!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,284
Laughlin, NV
Welcome to the forum!
I doubt your CH is actually that high, but I am sure it is high. Do you have a large amount of scale on the pool surfaces?
I believe your pool could be successfully exchanged to fresh water. The high calcium will work in your favor. I suspect the pool is also high in salt if the pool has not been drained for a long time, as the CH level suggests.
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.
 

Chismoso56

New member
Jul 21, 2019
2
Scottsdale, az
Thank you for the quick response and I'll read the recommendations! We have a very large amount of calcium built up on the waterfall/rock feature. Do you think it would be worthwhile to just pay to have the whole thing treated with reverse osmosis, or do you think it's worth trying to salvage by exchanging the water? We were quoted ~$900 for reverse osmosis, and a pump rental is $44 daily (or $528 for 4 weeks). We're worried the solutes might be damaging the pump/pipes, etc.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,284
Laughlin, NV
You will want to get rid of the scale buildup via bead blasting or other means before exchanging the water.

You can buy a low powered sump pump, mine is 1/2 hp, from Amazon or Harbor Freight for under $100.

Remember, with RO, you still will need to add 25% or so of new water.