Why does my pool shop think calcium is not important for me?

[bgpbucko]

I have my own DPD-FAS kit to measure my own pH, Cl and sometimes TA levels. Once or twice a month I go to my local pool store so they can measure my Salt and CYA levels (too cheap to get my own test gear for these probably). Pool is pebblecrete (the pool store system knows this).

This pool store is generally good because they offer free testing and don't pressure customers in to buying anything (eg if any level is low, they tell you what to add but dont then try to sell it, they will wait till I ask else assume I have the chemicals). Their test setup is pretty neat too, some fancy computer one that prints out all the levels.

Anyway, every time I go for a test, they ask if I have a gas heater. I asked why this matters and they mentioned something about calcium and scale. Then they said as I don't have a heater the calcium level doesnt matter. But now I realise it really does matter to keep it at ~250ppm. Current level is ~100ppm.

So clearly they are likely wrong and I'm working on getting Ca up to 250 again.

My question is - why would they consider Ca unimportant in my pool? Is there some aspect I'm missng? I'm in Sydney, Australia (similar climate to LA).

 

[Texas Splash]

Anyway, every time I go for a test, they ask if I have a gas heater. I asked why this matters and they mentioned something about calcium and scale. Then they said as I don't have a heater the calcium level doesnt matter. But now I realise it really does matter to keep it at ~250ppm. Current level is ~100ppm.

Welcome to the forum! Usually we hear (mistakenly) that pool stores try to say you need more calcium than what's required to protect heaters and old metal lines, but that's an old industry practice no longer required today. Even if that's why they are saying that (since you have no heater) it doesn't make it right. If you have a plaster pool the CH level is extremely important. (PS - Make sure to update your signature with all of your pool and equipment info). Below in my signature is a link to TFP's Recommended Levels. Click on that and ensure all your levels are in those ranges for best success.

You should also consider checkling with Clear Choice Labs for a proper test kit since that's about the only company that provides a good kit to your area. It will make a huge difference in your water management and save you a trip to the pool store. Hope that helps. G'Day!

 

[AUSpool]

Geday bgpbucko and welcome to the forum,

Your pebblecrete pool is a concrete pool, hear at TFP you use the plaster option. For a concrete or plaster surface a calcium hardness, CH, of 250 - 350ppm without a SWG or 350 - 450ppm with a SWG is recommende. I target the low side of the range because my top up water adds CH and it slowly creeps up over summer.

The Stores Spin Lab tests total hardness (TH) and we don’t care about the magnesium part of total hardness. Ive found the store hardness and salt tests to have the greatest variance from actual values. Doddgy tests and poor advice is why TFP recommends self testing. I’m suspect of your hardness value. Sydney tap water has ~60ppm total hardness. Replacing evaporated water with tap water will slowly increase your CH, loosing pool water due to heavy rain will decrease it. I would recommend a CH kit from CCL, Clear Choice Labs – Simple. Accurate. Fast. , or complete kit and test it yourself.

Other than thinking you have a vinyl or fibreglass pool I have no idea why they don’t recommend adjusting a low CH value. Are you sure your not confusing CH for total alkalinity (TA)? Is your FC test a colour matching test?

 

[bgpbucko]

Thanks for the feedback - looks like they just don't really see know about the importance of Ca (its definitely CH not TA).

My CH doesnt creep up too much as a lot of my loss us due to backflushing fairly regularly (the Kreepy seems to pick up a lot of grime, I'm close to an industrial area). So I will try to get to ~300 for now (a huge improvement already).

My cell also went through stages of picking up a lot of scale each month or so, that wouldn't dissolve in acid but need to be scraped off with a lot of effort and a plastic scraper. I replaced it on Friday with a self cleaning SWG to hopefully reduce that significantly.

I'll have a think about the test kit upgrade - though the pool shop is 5 mins away and I see their setup is a palintest, so not too worried about the accuracy.