Low Chlorine after algaecide

[Mr Bruce]

If you are very reluctant to drain and refill, your minimum FC is 9 and your target is 14. It's doable, but not easy.

I'm not sure what a "chlorine supplement" is.

 

[domct203]

Here are the results, double-checked for accuracy:

FC 7.5
CC 0
CYA 120 (1:1 dilution method)
pH 7.7
TA 70
CH 850 (double checked)
Salt 3600

I'm really hesitant to partially drain and refill at this point due to water restrictions and cost.
Recommendations, including type of chlorine supplement if I need it.

Thanks,
Russ

Your proper FC level is a percentage of your actual CYA level. The absolute minimum FC is 7.5% of your CYA. Never, ever let your FC reach or go below that level. Your daily target FC level (what you expect the FC level to be at your next day's test) is 13% of your CYA level. Shock level for a SLAM is 40% of your CYA level.

Stay on top of that FC level, or you will be SLAMing at 48ppm.

Your CH is very high as well, and you may be at risk for calcium scaling. If you enter all your levels into pool math it will tell you your CSI index.

CH is lowered the same way as CYA, water exchange.

 

[Russmd]

If you are very reluctant to drain and refill, your minimum FC is 9 and your target is 14. It's doable, but not easy.

I'm not sure what a "chlorine supplement" is.

I meant which type of chlorine product to use as I can't get that high with just the cell. I think liquid bleach will be the answer since the calcium is so high?

Pool math gives me a CSI of 0 so not out of range. I'll keep the FCl up to 9 for now, maybe drain and refill (recommends half for the CYA and less for the CH) when it cools down.
Thanks.
Russ

 

[Vickery]

You might consider a water softener. I didn't think I needed one for 28 years, then moved to a house where it was a necessity. Only then did I realize what a difference they make.

 

[Isaac-1]

Keep in mind that the pH test is only valid at FC levels up to about 10 ppm, if your FC is over 10 the pH test it will falsely skew your pH readings which will effect your CSI. My advice is to partial drain and refill as soon as possible.

Ike

p.s. and stop using all that stabilized chlorine

 

[Russmd]

You might consider a water softener. I didn't think I needed one for 28 years, then moved to a house where it was a necessity. Only then did I realize what a difference they make.

I was actually thinking about this given the high calcium content of our water and all the cell scaling I get. I'm interested in what kind of system is recommended, easy, and cheap? Will the usual salt exchange system cause me problems with raising the sodium salt levels in my salt pool?

 

[pooldv]

It is fairly easy to prevent scale in your pool and your cell by managing your CSI. Maintain CSI between -0.3 and 0 to prevent scale. PoolMath will give you the number after you enter all your test results. Tweak PH and/or TA to adjust. More here, Pool School - Calcium Scaling

 

[Russmd]

It is fairly easy to prevent scale in your pool and your cell by managing your CSI. Maintain CSI between -0.3 and 0 to prevent scale. PoolMath will give you the number after you enter all your test results. Tweak PH and/or TA to adjust. More here, Pool School - Calcium Scaling

Thank you. As I said a few posts above, I did the pool math and came up with a CSI of 0. My CH was 850 as our water is very hard. Despite the CSI zero I still get a lot of scaling, especially on the SWG requiring frequent cleanings. I'm afraid it'll fail prematurely because of this and my need to run it hard to maintain FCl levels in our environment.
For this reason, I'm thinking a conditioner on the fill water may be useful. I'm looking for options and wondering if that'll make NaCl a problem.

 

[pooldv]

Lower your CSI to -0.3 and it will help. If it still scales lower it more, as low as -0.6. CSI at 0 will prevent scale in the pool but may not prevent scale in the swg. Sometimes lower CSI is needed to prevent it in the cell. The main thing that will contribute to premature cell failure is frequent cleaning.

 

[Russmd]

Lower your CSI to -0.3 and it will help. If it still scales lower it more, as low as -0.6. CSI at 0 will prevent scale in the pool but may not prevent scale in the swg. Sometimes lower CSI is needed to prevent it in the cell. The main thing that will contribute to premature cell failure is frequent cleaning.

Do you recommend I do that by lowering the TA down to 50 or so by adding acid down to 7.2 and aerating?

 

[Vickery]

The newer models do a good job of scavenging the salt back out of the filtered water, very little will show up in it. Depending upon your water condition, you can address iron and sulfates as well as calcium and magnesium with the right models. While you don't get a lot of rain out there, you may have some splash out. I would doubt that softened water would be an issue for the swg. There are a lot of different units, from fairly reasonable to stupid expensive. Many of the softener installers will have a terrific song and dance, but if all you want is soft water and not entertainment, get one from a big box store and install it yourself. The biggest challenge may be finding a location for it.

 

[Russmd]

Thanks!

 

[max2k]

The newer models do a good job of scavenging the salt back out of the filtered water, very little will show up in it. Depending upon your water condition, you can address iron and sulfates as well as calcium and magnesium with the right models. While you don't get a lot of rain out there, you may have some splash out. I would doubt that softened water would be an issue for the swg. There are a lot of different units, from fairly reasonable to stupid expensive. Many of the softener installers will have a terrific song and dance, but if all you want is soft water and not entertainment, get one from a big box store and install it yourself. The biggest challenge may be finding a location for it.

offtopic but since OP is asking: real softeners work on the idea of replacing Ca ions with Na ions in ion- exchanging cylindrical tanks filled with special polymer granules. As you can see there's no scavenging of the salt, quite the opposite: hard water gets replaced with salt one. Since the initial hardness say 200 ppm the output 'saltness' is about the same 200ppm while human taste threshold is 2000ppm so you won't feel a thing . Because of this replacement softened water is not suitable for irrigation as the salt accumulates in the soil after water evaporates and will eventually kill everything.

The polymer eventually loses all its Na ion supply and needs to be regenerated. Regeneration is done by system of valves from very concentrated salt solution so overall you'd need to add salt to the second 'brine' tank once or twice a month. Some water gets washed to the drain during regeneration process so it presents certain plumbing challenge. That system of valves is often combined with a timer as a single assembly sitting on top of the ion exchange cylinder and it is often simply called 'valve'. This 'valve' defines how much headache are you going to have with the system as polymer granules can be bought separately. Polymer is getting contaminated and eventually would require replacement in about 10 years of cycles if you have pre- filters against chlorine and iron. If not- depending on those contaminant's concentration polymer would require replacement much sooner, in about 2-3 years. The cost of polymer- around $200 for the whole house system IIRC. The well known brand famous for reliable 'valves' is Fleck, their 7XXX series is what you should be looking for. Water softeners 'dealers' simply put together the 'valve', cylinder with polymer and their own label and sell it in very wide price range while you're getting pretty much the same system if it uses the same 'valve'. Some of them add grossly overpriced pre- filters which are necessary but should not cost that much.

There are other 'systems' which are essentially filters and as such cannot change water hardness at all. They're sold as 'salt free' and IMO are just snake oil of water filtering industry. Pretty much as mineral systems for pool care or even worse.

 

[pooldv]

Do you recommend I do that by lowering the TA down to 50 or so by adding acid down to 7.2 and aerating?

I would lower TA to 50. You can do that slowly by lowering PH to 7.2 and letting rise to 7.5 or 7.6 and repeating. Or you can do it actively following this, Pool School - Lower Total Alkalinity

 

[Russmd]

Thanks. I have a softener system for my house water (not close enough too plumb for pool). The company comes and replaces the exchange tank every two weeks, costs me less than $25 a month. I talked to them - they have a tank 1/3 the size which they can put onto the automatics filler line. I can get it recharged on a schedule or just when I call for under $20. I might try it, if I I decide to go with it I'll test the output frequently and get an idea of how often I'll need it done. My only concern is if that Na output will cause me a different problem in my salt pool.

- - - Updated - - -

I would lower TA to 50. You can do that slowly by lowering PH to 7.2 and letting rise to 7.5 or 7.6 and repeating. Or you can do it actively following this, Pool School - Lower Total Alkalinity

'

Maybe I missed something but what I said about lowering the pH then aerating is per pool school. Is there something else?

 

[pooldv]

Not really, you are on the right track. You can lower PH to 7.2 and not aerate and PH will rise on its own without aeration.

 

[max2k]

Thanks. I have a softener system for my house water (not close enough too plumb for pool). The company comes and replaces the exchange tank every two weeks, costs me less than $25 a month. I talked to them - they have a tank 1/3 the size which they can put onto the automatics filler line. I can get it recharged on a schedule or just when I call for under $20. I might try it, if I I decide to go with it I'll test the output frequently and get an idea of how often I'll need it done. My only concern is if that Na output will cause me a different problem in my salt pool.

- - - Updated - - -


'

Maybe I missed something but what I said about lowering the pH then aerating is per pool school. Is there something else?

that is new to me- looks like they do regeneration at their location or it is one of the 'filter' systems altogether. Please find out details how it works to be sure what kind of chemicals would go into your pool at the end. Pool presents unique challenge as it tends to concentrate contaminants over time so if they output something besides Na I'd love to know what exactly. Na should not be a problem for your salt pool as you need to have around 3000ppm of salt anyway so if anything it will reduce salt demand for your pool. This of course depends on hardness of your tap water so I'd measure that first.

 

[Holydoc]

Russmd,

I am also rather new here and discovered the same thing you found. I was adding my usual 64 ounces a night of liquid chlorine when I noticed that I had some (probably 6 ounces) Polyquat 60 (algaecide) sitting in the storage box. I decided "What the heck, I will just dump it in tonight with the chlorine just to get rid of it". Well the next day when I tested my water right at sunset instead of being the expected FC 7.5, it was FC 4.5. Not only was this much lower than expected, it was under my minimum FC 5 (at CYA 70). I went into instant worry mode with all kinds of questions running through my mind.
Why was the FC off?
Was this a sign of algae?
Did someone have a swim meet in my pool while I was at work?

Then I remembered that I had dumped that old algaecide into my pool. Ugh! If I had just stayed the course, these type of surprises would not happen.

Well I just wanted to encourage you that going the TFP route has been both educational and rather satisfying. It becomes so routine that when something changes a little, you will be able to knock it out immediately. Welcome aboard.