SWG newbie-salt questions

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sueasinsue

sueasinsue

0
Aug 3, 2016
56
syracuse NY
How often does your salt pool ask for salt? Weekly? Monthly? This morning my nano-machine was asking for 52lbs of salt and a warning light was going off. The last time this happened I ended up with low CYA and had to add stabilizer for a few days which was the reasoning behind it asking for salt. I added 25 pounds of salt this morning. I tested the water at 11am and my results are
FC 13
CC 0
CH 250
TA 180
CYA 60
PH 7.8
CL 5
BR 10

The FC and TA seem high? But the CYA is right around what it should be?
 
It all depends on splash out and rainfall, these are the only two things that remove salt from a pool. The more rain overflowing the pool the sooner you will need to add more salt.
 
I'm noticing a couple of things that are out of sorts.

First, you FC is too high for your CYA. Were you super-chlorinating with the SWG or otherwise trying to shock chlorinate your pool?

Second, your TA is very high. At 180ppm it is going to cause your pH to rise quickly.

Third, based on the numbers you have provided, your CSI is +0.36, that is scaling territory. When you operate an SWG pool, you want to maintain a zero to slightly negative CSI, somewhere between -0.1 and 0 (you can go all the way to -0.3). The reason being is that the pH inside your SWG cell is much, much higher than your bulk pool water. The pH inside an SWG cell when it is generating chlorine can easily go up to 11. So, if your CSI is already very positive before the cell is running, it is going to go up even higher when the cell is running. This will cause calcium scale to build up on your cell plates and is very likely the reason why your cell is asking for more salt. When an SWG cell plate gets scaled with calcium, the effective surface area for generating chlorine decreases and, from the standpoint of the electronics, that looks like the salt level has decreased. This is a common error made by SWG owners - they see the low salt alarm, add salt to compensate and the problem temporarily goes away. Then more scale forms, they keep erroneously adding salt and, the next thing you know, your pool water has too much salt in it.

So please try to lower your TA and keep your pH in the 7.6-7.8 range. Getting your TA below 100ppm and closer to 80ppm should lower your CSI to an appropriate range. You will also want to pull your SWG cell and check it for calcium scale. If the plates appear to be a whitish-grey, then they need to be acid cleaned according to the manufacturers specification.
 
To answer your questions-
It rained all day yesterday.
No I didn't add any bleach or anything when I was raising the CYA-just stabilizer. I did the test for FC twice because I thought that seemed very high and I did something wrong. Same results.
I had the cell and filter running all night for 24 hours because we used the pool a lot on Saturday. When I first checked the nano-cell it didn't ask for salt 20 minutes later it was asking for salt.
I thought I saw something in Pool School about lowering TA...I'll go read that again. I do have some PH-down chemical I bought last week when I saw my ph was at 7.8 however someone on here told me not to add it as SWG's tend to settle at 7.8. I am not sure how to take the SWG cell apart? I did clean the screen in it when the nano machine told me to, but not sure where these blades are? I'll see if the manual that came with the machine has anything on that. Thanks!
 
If you need to lower pH, please do not use solid pH-Down chemicals. Solids, granular acid (pH-Down) is almost always sodium bisulfate. It lowers pH but it is not compatible with SWG's because the sulfates will attack and destroy the coatings on the SWG blades. Also, sulfates are not good for plaster pools and once the sulfate level rises above 300ppm, you can get a problem called "sulfate attack" (basically the sulfates weaken plaster and cement surfaces). If you need to lower pH, you should use muriatic acid as it is completely compatible with all pools.

Yes, Pool School does teach how to lower TA - Pool School - Lower Total Alkalinity . Basically it involves cycling your pH down to 7.0-7.2 (which consumes TA) and then allowing the pH to come up naturally through aeration. It helps if you have a waterfall or spa or some source of mechanical aeration to your water (kids splashing around works too!). Then, once your pH gets back up to 7.6, you hit it with acid again to lower to 7.0-7.2. Each time you add acid, it lowers the alkalinity. So you just keep doing the acid/aeration cycle until your TA is down to 80ppm.
 
sueasinsue said:
Yikes! Why would the pool store sell me ph-down I told them I had a salt water pool?
I don't have any sort of aeration and I don't have a plaster pool either. It's above ground. I guess I will look for muriatic acid then....
Click to expand...

One more reason to never set foot in a pool store....they will sell you anything they can REGARDLESS of whether or not you need it. I see you're new here, so welcome. You should avoid pool stores at all cost and be sure to invest in one of the test kits we recommend. You are completely capable of testing and balancing your own water and most pool chemicals you need can be found in hardware stores, grocery stores or big box stores like Walmart. So there's really no need to ever go into a pool store unless you want to pay high price for some pool noodles.

I saw you have an AGP after I posted so ignore the plaster/cement issue. It is still an issue for SWG's and, while you probably would have enough rain dilution to handle the sulfates, why risk it? Muriatic acid is a little bit trickier to use because the high strength stuff (31.45% or 20 Baume) does fume a little and can smell awful (but it's not going to kill you so don't freak out if you do smell it) but it is much better to use in a pool because all it adds to your water is a little extra chloride (salt) which your SWG is using anyway. Just be careful when using it and practice basic chemical safety and you'll be fine.

You can get MA in a pool store but it's not the cheapest there usually and they will likely try to talk you out of it. You can get it in most hardware stores pretty easily (either in the paint section or in the outdoor section, just ask for it).
 

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sueasinsue said:
Ok good, there is a home depot not far from me. That goes right into the pool water over the edge of the pool correct?
Click to expand...

Well yes, but carefully. You only ever pour acid into the pool water SLOWLY in front of one of your return jets (think a pencil-width stream as you pour). Muriatic acid has a specific density quite a bit higher than water and just dumping it in will cause it to sink to the bottom and sit there. It is always a good idea to brush your pool after adding any chemicals to help promote mixing.
 
Yes, pour it in front of a return with the pump running. A little goes a long way, better to add 1/2 to 2/3 what Pool Math says, let it mix around and then test again. That stuff is strong and you can over-shoot if you aren't careful. And keep your face up-wind the best you can, the fumes are very strong.
 
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