Testing for CH - other methods and how to lower?

[nickadee]

Hi all,

I think I have high CH. I'm not sure of this as I don't have a tester, and can't seem to get hold of one where I live (the pool guy had never heard of testing for Calcium). I have eliminated all other problems but still have dull, cloudy water.

My numbers are:

FC - 4
TA - 80 ppm
PH - 7.6
CYA - 50 ppm

While I track down a test kit, is there an alternative way that I can determine whether it is my CH that is the problem?

Also, I am hoping that there is an alternative to draining my pool to lower CH if it is the problem. It is 230 000 Litres so to have to dump even 10% of the water and refill takes a day.

Thanks,

 

[chem geek]

Nick,

With your other numbers, I doubt that the problem is high CH causing the cloudiness. At 300 ppm CH, the pool would be about in balance, and even at 1000 ppm CH it would be +0.35 which might be ever so slightly dull looking, but not what one would call cloudy (and these numbers are for 525 ppm TDS -- for a salt pool, they would be lower). If the problem is truly with calcium carbonate saturation, then you could just add Muriatic Acid to lower the pH down to 7.3 and if the water clears up then perhaps that is indeed the problem; if not, then it's something else. See if you can get a test kit from tftestkits or a Taylor K-2006 from SPS (they are similarly priced for the volume of tests as the TF100 from tftestkits has 36% more volume and is more intelligently packaged). I noticed from other posts that you are in Australia so these test kit options may not be available to you, at least not directly. You should be able to get a test kit that tests for Calcium Hardness -- that's pretty much essential for a plaster pool.

Given the large volume of your pool, it's more likely that the circulation may be poor and/or filtration isn't as good as it should be. Perhaps the filter should be looked at or you need to run the pump longer to increase the turnover rate. Are you at one turnover per day currently?

If your chlorine consumption seems unusually high, then you could have algae growth, though at the chlorine and CYA levels you have this would probably only happen if your phosphates level was quite high -- probably above 3000 ppb -- and that would be the last thing to address after eliminating everything else. You noted elsewhere that you have a salt pool so I presume you have a saltwater chlorine generator (SWG). It's unusual to have algae in such a pool at the chlorine/CYA levels you have -- again, unless the phosphates level is through the roof.

Those are my thoughts. Others may have additional suggestions.

Richard

 

[nickadee]

Hi Richard,

thanks for the quick response.

I spent this afternoon cleaning out the sand filter. It was pretty dirty so maybe that will make a difference.

It has been cloudy for a few weeks, but because of the heavy rains we have had up here its been hard to keep chemical levels perfect. I have ordered 700kg of salt though to get that back up to speed.
I shocked the pool about 4 days ago thinking that it might have been an algae growth, but it didn't seem to do anything so i have started looking for different reasons it would be cloudy. At the moment I can't see the bottom of the pool at the shallow end (1.3 m deep) the pool is a nice blue colour, just very cloudy. I am thinking that if it is calcium because i have been adding Calcium hyphchorite (its the only chlorine i can get in my town, and i bought both supermarkets out of bleach last week - it takes alot of bottles of 3.6% bleach to shock such a big pool).

So after your advice Richard, I have left the pool circulate overnight tonight and the big drain is open, the filter is clean so we'll see if that does anything while i wait for a test kit to be sent from Melbourne. (My test kit only does FC, TA, PH and CYA)

Thanks for your help,

nick

 

[nickadee]

so it has been circulating for 24 or more hours and it is still quite cloudy, i don't think there has been a change..

TA has dropped from 80 to about 60 overnight though,

PH is 7.4
FC 3
CYA 50

I will have the test kit on wednesday hopefully so I will post my numbers then including CH and see if you can help me.

Thanks,

Nick

 

[duraleigh]

Hi, Nick,

While calcium can cause cloudiness, it is infrequently the source. More common is not enough circulation and not enough chlorine. Your pH is perfect (further reducing the chance of calcium being the culprit) and your CYA is fine. I would shock your pool and run your filter 24/7 backwashing as necessary. It may take another 48 hours but I think you'll see a distinct improvement.

Bring your FC up to about 15-18ppm and KEEP IT THERE by testing and adding enough Cl to get it back to that level at least twice a day....more often if you have time. This constant high level of chlorine will kill any organics in your pool and the constant circulation will get out all the visual cloudiness.

That said, it may be calcium as the culprit but that wouldn't be my first choice.

 

[nickadee]

My old test kit only goes up to 5 ppm for chlorine. I bought some test strips that go to 10.. I will get more bleach from the supermarket, but generally I buy them out and I have to resort back to calcium hypochlorite to top up.

Hopefully my new kit will go up that high. Thanks Duraleigh I will give it a go, I'll try anything at the moment.


Thanks,

Nick

 

[nickadee]

Hi Richard,

I have just recieved my CH test kit, and it looks like you were right. CH is around 300.

So even though I shocked last week (I went up to around 10 ppm FC for 8-10 hours) it wasn't enough?

My next dilemma is that people are using the pool all the time (We own a backpacking hostel) and to close the pool again is going to cause drama's. Can I maybe use and algecide to kill the algae so I don't have to close the pool or is shocking up to the 14-18ppm FC the only way to do it?

Thanks,

Nick

 

[duraleigh]

So even though I shocked last week (I went up to around 10 ppm FC for 8-10 hours) it wasn't enough?

Nope! You need to bring your FC up to at least 15-18ppm and.....here's the key......HOLD IT THERE until your pool is clear. Again, it may take 24-48 hours but until you hold the FC up at that level and clear the pool, you will probably continue to have cloudy water.

I would be perfectly willing to swim in a pool when the FC was that high....others on the forum may take exception to that......personal choice. It's the combined chloramines (of which I think you may have an abundance) that cause the stinging and chlorine smell......shocking effectively will rid your pool of them

PS - I missed Richard's post so I ended up repeating a lot of what he said....he also said it better than I did.

Algaecides are seldom adequate for clearing a pool. They are good at prevention but not actually killing.

 

[nickadee]

lol, i'll just put a little sign on the gate letting people know that there are high chlorine levels. Swim if you dare..

Thanks for you help, I'll start shocking again in the morning, this time until its clear!! hopefully this will be the end of my pool troubles (for a bit)..