high calcium

[alisonquilts]

I finally have my new testing kit (K-2006C), and I am enjoying revisiting basic high school chemistry labs. Most of my numbers are good (see below) but my calcium is way too high. Partly this was due to me buying into the pool store mantra, and partly due (I think) to the pool store test being grievously inaccurate - the last test I have from them was three weeks ago, after I had added the last of the calcium they recommended, and read 275 ppm; my test today (done three times out of sheer disbelief) reads 420 ppm!!

I have a SWCG and I am not seeing any scaling problems so far with this Ca++ level, but I would prefer to deal with it and get it down. What I am thinking of doing is sucking water out of the deep end through the bottom drains (with the pump on 'full drain' setting, no skimmer, and water going to waste) and simultaneously have a couple of hoses of tap water pouring into my shallow end. (Tap water CH is 40 ppm.) I feel this is the best way for me because of the extreme shallowness of the shallowest part - 9" - and the need to keep a certain depth over the liner at all times. Here's my question: what is the minimum depth of water (and thus weight) required to keep the liner from lifting? 4"? 5"?

Thanks in advance for any advice, or suggestions!

Alison

test results, midday, water temp 81F:
pH 7.8 (going to dump in 1/2 gal muriatic this evening)
FC 2 ppm
CC 0
TA 100 ppm
CYA 50 ppm (going to the pool store to get more tomorrow)
CH 420 ppm (aaaahhhh!!)

[aylad]

Hi Alison,

The plan you have mapped out sounds like a good one, but you might want to hold on until Pooldoc sees this thread, because he's been describing on other threads a method of calcium removal using cal-hypo (don't ask me, HE's the Pooldoc!!). Might want to let him comment on which would be a better way for you to go, before you waste that much water.

[PoolDoc]

I have a SWCG and I am not seeing any scaling problems so far with this Ca++ level, but I would prefer to deal with it and get it down.

Uhm. If it's not broken, why are your trying to fix it? 420 ppm is a number; not a pool. It's your pool that's the issue (or non-issue), not the the number. It doesn't damage your SWCG to scale up. If you clean every 3 months, as may be recommended, and have no problems, well, you have no problems.

If you want a larger margin of safety, why not strip your carbonate alkalinity (hold your pH to near 6.8 and aerate -- covers OFF!), and then re-buffer with borax.



I feel this is the best way for me because of the extreme shallowness of the shallowest part - 9" - and the need to keep a certain depth over the liner at all times. Here's my question: what is the minimum depth of water (and thus weight) required to keep the liner from lifting? 4"? 5"?

I don't know; it depends on things like how wet ground around your pool is.

Also, I don't see any point to draining and filling at the same time. If you want to do an in-place water replacement, you need a membrane (like an oversized winter cover) to separate the old and the new water.

[alisonquilts]

Thanks aylad and PoolDoc!

I won't try to fix the unbroken system if it remains unbroken...but we've only been operating at this level of Ca++ for a month, and I want to have a plan in case things start to act up.


Also, I don't see any point to draining and filling at the same time. If you want to do an in-place water replacement, you need a membrane (like an oversized winter cover) to separate the old and the new water.

I was hoping that water mixing would be minimized with the shallow end being forty feet (horizontal)ly and eight feet (vertically) away from the deep end drains, and with no water agitation from the return jets. Do you think the "new" water would sink to the deep end level that quickly? (I don't know - tap water is a good 20 F colder than our pool water...maybe its density would be enough to make it sink really quickly. On the other hand, it would have to go around a corner as well.)

I'm certainly not looking for extra work...so I'm glad that it sounds like I can postpone this indefinitely!

Alison

[PoolDoc]

I was hoping that water mixing would be minimized with the shallow end being forty feet (horizontal)ly and eight feet (vertically) away from the deep end drains, and with no water agitation from the return jets. Do you think the "new" water would sink to the deep end level that quickly.

Well, you'd get a little less mixing than if you put the pump and hoses BOTH in the deep end. But not lots less.