High CYA Red water clear. FILTER SOCKS V STIFF. WHY?

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Re: High CYA and therefore high FC levels. Is it safe? HELP!

FC has to be above the minimum level for your CYA (30 in this case) and below shock level (75(!)). At least that is what I believe the conditions for safe to swim are.
 
Re: High CYA and therefore high FC levels. Is it safe? HELP!

I am not certain at that high of cya level what the "safe" swimming level is. It may follow the rule of "below shock level for the cya level" but your pool cya level is so high...I have not encountered (or have been able to find) discussion of it.
 
Re: High CYA and therefore high FC levels. Is it safe? HELP!

When you get to extraordinarily high CYA levels, then we need to account for the fact that chlorine bound to CYA is not actually completely inert as we have been assuming, but that it is far less reactive than active unbound chlorine, hypochlorous acid. Based on this paper, the chlorine bound to CYA is at least 150 times less reactive than hypochlorous acid. So while normally we would say the minimum FC level to prevent algae growth with a 400 ppm CYA would be 7.5% of 400 or 30 ppm, that 30 ppm FC is mostly bound to CYA so might be equivalent to 30/150 = 0.2 ppm of hypochlorous acid which is in addition to the 0.03 ppm hypochlorous acid that is unbound.

The problem is that there are no studies and no significant numbers of actual reports at such high levels to know whether the chlorine bound to CYA is actually effective against algae. If it were, then using the 7.5% rule at 40 ppm CYA for a 3 ppm FC would have 3/150 = 0.02 ppm equivalent hypochlorous acid from the bound chlorine and 0.03 ppm from the unbound active chlorine for a total of 0.05. With 400 ppm CYA, one gets that same total with 6.5 ppm FC. We have seen pools with 6-7 ppm FC and 200 ppm or so CYA that had algae so I would say that we can't assume the chlorine bound to CYA is this effective.

So unfortunately we have to be conservative here and say that 30 ppm FC is the minimum at 400 ppm CYA. It could be less and probably is less, but we don't know by how much.

Of course, the right thing to do is to start with water dilution to get the CYA level down.
 
Re: High CYA and therefore high FC levels. Is it safe? HELP!

Thanks for all that info Chem Geek. One thing I did not mention before- and it may not be relevant- but we have a lot of iron in our well water. We are using water which is filtered through our crystal filtering system and then softened, but I am aware when cleaning the filters that there is a sizeable amount getting through. We are back washing the crystals between sessions of filling the pool, but although the system is man enough for the house and our uses, it is obviously not for re filling the pool. Could this be altering the results?
 
Re: High CYA and therefore high FC levels. Is it safe? HELP!

I was concerned not about the softener, but the excess iron getting into the water and affecting the results.
We intend to empty the pool tomrrow morning (apart from a foot to hold the liner). We will refill directly from the well this time which means we have to use flocculant to get rid of the iron and then get the solids hoovered out.
Once we have done this, is it best to start with PH level and then go on to Chlorine? Should we shock the pool first? We are going to change over to bbb, so I am wondering how much 5% bleach we would need to shock 23kgallons. And how much baking soda we are likely to need to achieve good levels of PH.
 
Re: High CYA and therefore high FC levels. Is it safe? HELP!

Have almost emptied the pool, having decided that there is no option apart from that to lower the CYA of 380. We will refill over the next two or three days. This time, we are using our well water which has a very high iron content, so we will need to use flocculant and get the solids removed. After that, please could someone let me know in which order I should do things. I think it is to raise the PH first and then to shock. I want to try to follow the bbb system to avoid raising the CYA again. We have only managed to source 5% bleach here in Italy. We will try to find liquid chlorine but I am not holding my breath. Obviously I will do the tests and post them, then could someone talk me through the amounts I will need to use. I am fighting my partner as he wants to use the Dichlor to shock the pool initially, but I am desperate to try to avoid raising the CYA which will possibly still be 50 or so, because of the residue of water we are leaving in the pool ( vinyl). Thanks to all for your help and encouragement so far.
 
WAS HIGH CYA NOW LOW -20. Refilled. VERY RED WITH IRON. HELP

Pool now refilled. DARK RED with iron from the well water. Have got the CYA down to about 20 from 400. Have been told to shock the pool and circulate and then once FC level is down to normal, to use FLOCCULANT. leave it to settle and then get the solids hoovered out. (This os what was done when the pool was installed 5 years ago) Can anyone advise how much flocculant we should use- we have been told 5 litres. We have roughly 12 times the amount of iron normally in water. PH 7.6.
Intend to shock with Dichlor to raise CYA a little and then go to bbb system.
 

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VERY RED WATER. USE PF FLOCCULANT

Merged threads. Please keep all questions in this thread until pool is completely under control. :wink: Thanks, Butterfly

Have refilled pool this time from our well, which we know has 12 times usual amounts of iron- for the house we have a crystal filtering system which removes it and stops staining.

We have been told we need to start by shocking the pool and as the CYA level is now so low,( 20 from 400) just this once intend to use Dichlor.
PH is 7.6

After the FC level has dropped back to normal, we have been told to use Flocculant. We have read up about it and there seem to be very different methods- ie running the pump for hours or not running the pump at all and letting the flocculant do it's work separating the solids to the bottom. i trust you guys and know that someone will have experience in using it. We are using the powder, not the tablets.
How long should we leave the flocculant before calling in the guy to hoover?
After the iron solids are removed, what next?
 
61761

Topics merged.

Sorry to butt in to your thread, but we are about to use a flocculant to remove the iron from the well water ( very dark red ) with which we have refilled the pool. We Have shocked the water and are circulating it. I will test the levels again tomorrow. Before I started, the CYA was down to 20 from 400 and the PH was 7.6.
I am told we should wait until the FC is down to normal levels before using the flocculant.
My 2 questions are:
How long should we keep the pump running having shocked the pool? Is it until we reach normal levels of FC?
And. Once we put the flocculant in the pool, what do we do? I have read various schools of thought. Some say just sprinkle and leave. Some say circulate the water for hours and then leave. I've have someone standing by to Hoover the deposits once they have sunk to the bottom, but we are just not sure of the best routine to get to that point!
 
SHOCKING POOL- waiting to use Flocculant. High PH.

Merged threads. Please keep all questions in this thread until pool is completely under control. :wink: Thanks, Butterfly

We are in the process of shocking the water of newly refilled pool which is very red with iron. The pH is high- 7.9. Can we lower it with Muriatic Acid to help avoid the vinyl staining? The next step is to use a flocculant to separate the iron solids to the bottom of the pool. Would the Muriatic Acid have any detrimental effect(s) on either of these processes?

FC 13.5
TC 0
CC 0
PH 7.9
TA 380
CYA 20
 
Re: High CYA and... Edit: DO I NEED TO USE A FLOCCULANT?

Do I need to use flocculant as we have kept the pump running for 3 days, cleaning the filters regularly and now have sparkling clean water (instead of the dark red) with some loose deposits on the walls and floor. We were waiting for the FC to drop to 3 or less before using the flocculant, but I now think it might be possible to use the Hoover on the pool ourselves now, rather than using the flocc and calling a professional in to hoover the deposits, especially if we clean the filters often and go gently so as not to disturb the deposits. Is it likely that there is much more iron invisible to the eye, suspended in the water? Any advice welcome please as to whether we should flock or not? We need to make a decision within the next couple of hours......
 
Re: High CYA and... Edit: FILTER SOCKS HARD AND STIFF. WHY?

Can anyone help me with solving the hardness of our filter socks? We have been filtering a lot of iron out of the pool over the past few days and suddenly they have become almost like cardboard, although less red than when the bulk of the deposits from the water were being removed. Might lemon juice and salt mix work as it does to remove iron stains from the vinyl liner at the water level? Any tips? Should I try machine washing them?
 
The cartridges becoming stiff is usually the result of calcium scaling but the only CH number i see that you posted was 340 ppm and that's not really that high. It could be from the iron getting forced into the pores of the media. You can try the lemon juice and see if it works. I don't think it will hurt anything to try it.
 
Hi- I tested the water again this morning and TA is 330, CH is 320, PH is 8.0 FC is 2.5. The solids will be hoovered out at some point later today after floccing. Have the socks in a bucket with some salt from the house water softener and lemon juice in water. The trouble is volume! The ratio of lemon juice and salt to water may be too great. Anyway, the socks have been in the solution for about an hour and I think I can feel some improvement. I'll keep you posted. And thank you.
 

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