Low calcium hardness in vinyl pool ok?

[shaggy1050]

You only need to worry if the calcium level is too high--then your water can get cloudy (but it's still safe).

Pool stores will give you an AMAZING song-and-dance about why you need calcium in your vinyl pool. It's nonsense.

If you have a heater with a copper heat exchange and your hardness is low it can destroy your heater. If there are any exposed metal parts in your pump or filter then your water when it is too soft (below 150ppm) your water can be corrosive as well. Most newer pump and filters won't have any exposed metal though and you should be find. If you have a vinyl liner and no heater 150ppm is a good point to stay at if you have a heater I usually recommend 250ppm just to be safe.

[Watermom]

shaggy1050,
Welcome to the forum! By any chance are you in the pool industry in some way? Your post reads like you might be.

[PoolDoc]

Hi Shaggy;

Watermom asked me to take a look at your post -- she's right, it reads like you've been drinking a lot of the pool industry koolade, whether you are in the biz or not.

Several important points:

1. Low pH will damage copper pool heaters; low hardness does not.
2. Hardness -- at ANY level -- is only an issue in a 'plastic' pool (PVC pipes, vinyl liner, polymer pump) if it's HIGH. A hardness of 10 is fine in a plastic pool.

In general, the whole saturation index thing the pool industry has wasted so much paper on, doesn't apply to most pools. It's significant in PLASTER (cement & marble dust) pools, but overblown or inapplicable almost everywhere else. The entire situation is a mess.

If you are a pool owner, the answer is don't worry about it much unless it's too high, or unless you have a plaster pool.

If you are in the pool biz, this is a discussion that belongs in the China Shop.

Best wishes,

PoolDoc

[waste]

Hi Shaggy;

Watermom asked me to take a look at your post -- she's right, it reads like you've been drinking a lot of the pool industry koolade, whether you are in the biz or not.

Several important points:

1. Low pH will damage copper pool heaters; low hardness does not.
2. Hardness -- at ANY level -- is only an issue in a 'plastic' pool (PVC pipes, vinyl liner, polymer pump) if it's HIGH. A hardness of 10 is fine in a plastic pool.

In general, the whole saturation index thing the pool industry has wasted so much paper on, doesn't apply to most pools. It's significant in PLASTER (cement & marble dust) pools, but overblown or inapplicable almost everywhere else. The entire situation is a mess.

If you are a pool owner, the answer is don't worry about it much unless it's too high, or unless you have a plaster pool.

If you are in the pool biz, this is a discussion that belongs in the China Shop.

Best wishes,

PoolDoc

Speaking as someone in the business - GREAT ANSWER! (but I wouldn't know that, if I hadn't joined this site)

[chem geek]

There's a lot of discussion among the experts on whether calcium carbonate saturation helps to prevent metal corrosion and you can read just one such discussion here:

http://corrosion-doctors.org/Cooling...orrosivity.htm

The bottom line is that it is pH that is a critical factor in corrosion and next would be a low TA since that would allow for a low pH locally when there is no water flow. The presence of chlorides, sulfates and generally the conductivity of the water are also important. Of course, one must have an oxidizer in the water as well such as dissolved oxygen or, of course, in pools we have chlorine. Calcium carbonate saturation is iffy at best since getting a consistent protective patina is quite difficult to achieve. If calcium directly interfered with the corrosion process, then that would be different, but there is no evidence that this is the case.

Many people have copper plumbing in their homes and have either chlorine or monochoramine in their water systems yet the water is often very low in CH (50 ppm or lower). Water districts often add some corrosion inhibitors, but they don't saturate the water with calcium carbonate. Also, there is no CYA in tap water so any chlorine is far, far higher in active concentration than found in pools. Pools with an FC that is at or above the minimum in Ben's Best Guess CYA chart (an FC that is 7.5% of the CYA level) are equivalent in active chlorine concentration to water with only 0.06 ppm FC with no CYA.

[CarlD]

I would add that if hardness were good for plumbing we wouldn't have so many water softeners!

Everyone's left out that excessive hardness causes scaling and that's not much better than corrosion. Anything that uses a lot of water, from a coffee maker to your faucets are victims of scaling.

I think Richard's message (and mine would be) that proper pool chemistry maintenance is all you need--so skip the calcium in vinyl pools!

[expertmagician]

I know this is a very old topic...and I am new to this forum...But, I am a new pool owner of a semi-inground pool with a Hayward Gas Heater (150,000 BTU).

I do not knnow what the coils are made of...But, Hayward said that calcium should be at 200ppm - 400pmm. That sounded high and the guy I spoke too sounded new...reading scripts. (Must be sumemr help becasue the people I spoke to in the winter during my research were very knowledgeable).

In either case, I was wondering how to test for calcium and if I should keep it as high as 200pmm in my Vinyl semi-inground pool ?

Thoughts ?

Hopefully, I will turn my pool on this weekend after the electrician comes...this is the first pool I owned othet than a 10 foot round Intex.

[maryberrye]

Since I have a vinyl pool, I've taken Carl's advice and never bothered with the CH test. I am curious though what Ben's idea of a too high calcium reading is? We live in an area with very hard water - 469 ppm. Is this too high?

Thanks,
Mary

16k IG vinyl
FC 4.0
CC 0
PH 7.5
CYA 29
ALK 240 (working on it now)
temp 80