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Thread: Intex CS8110 Salt sensor question

  1. #1
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    Intex CS8110 Salt sensor question

    Does anyone know how the CS8110 salt sensor works?
    The unit comes on for ~1min, starts generating chlorine, then posts Low Salt, starts beeping and stops product chlorine. I'd like to bypass the sensor or at least try to so we can generate chlorine and I will manage the salt levels via periodic testing.

    The history:
    We've had this Intex CS8110 SWG working flawlessly for the last 2 summers with a sunken above ground pool, ~8800 gals. Early this spring the low flow sensor started to fail. I proved it by jumping the sensor and the unit would come on and generate chlorine as expected. I ordered a new one and continued to allow the SWG to operate with the jumper inplace, then replaced it once it arrived. Everything was great for a few days and then the Low Salt light/sensor posted. Instead of testing the water as I was under the belief that the sensor was accurate, I just added a bag or two of salt. It appeared to work for another week or so and started posting Low Salt again...silly me just added another 2-3 bags of salt thinking our splash-out was über-bad last summer given all the use. It actually worked for a few more days to maybe a week and it started posting the Low Salt again. After reading somewhere that a user actually had too much salt and it posted the error, I finally decided to go get the water tested and pick up some test strips. The salt was out of control...like >5000! My test strips showed in the 7500 range. Given I recall we should be around the 3000 range, I drained ~75% of water and got it back in check (currently ~3050). Fired up the filter for about a day and then tried the SWG again, Low Salt posts still in ~1min.

    Given my next step would be to replace the unit and I am fairly technically inclined (love tearing things apart), I thought I'd see what I can attempt to do to bypass the salt sensor so that the unit would not perform the check to possibly get one more season out of it.
    I've checked the simple items, like ensuring there's ~24v being output from the board to the connector, all the connectors appear to be fine as well as the board,etc.

    Any help/guidance would be greatly appreciated - I can post pictures and provide any further detail as needed. Thanks in advance!
    39,000 True L shaped 43 x 28 x 18 inground pool
    Hayward sand filter with Hayward 1.5 hp pump
    Aqua Comfort SWG

  2. #2
    Administrator JasonLion's Avatar
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    Re: Intex CS8110 Salt sensor question

    Welcome to TFP!

    You should check the cell for calcium scaling. Assuming the cell is clean then it is almost certainly wearing out and only yet more salt will get it to work and even that for only a limited time.

    I don't know for certain, but most of the inexpensive units like that one work by measuring the current across the cell plates. Higher current means there is more salt in the water. Unfortunately, the current goes down as the cell platting wears off and the unit doesn't know that and instead assumes that the salt level is going down.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. #3
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    Re: Intex CS8110 Salt sensor question

    Thank you very much for the quick reply!!

    I have kept the cell plates clean using the vinegar soak method every 6months or so and last time was while draining/refilling the pool recently so I could rule that out.

    Measuring the current across the plates would make sense as I do not see any other wires or sensors coming from the plates terminals to the board itself. I saw the price of the replacement cell and it's silly not to just get a new unit as a 2-3yr life is worth the money IMO. It really made maintenance a breeze and allowed us to enjoy the pool more with vacuuming the only 'major' task as the chemistry stayed quite consistent.

    I may tinker with this unit still while we shop for another one going into it knowing this will not be a reliable unit over time.

    If I come with anything useful I will share it here.
    Thanks again
    39,000 True L shaped 43 x 28 x 18 inground pool
    Hayward sand filter with Hayward 1.5 hp pump
    Aqua Comfort SWG

  4. #4
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    Re: Intex CS8110 Salt sensor question

    My SWG just started doing the same thing a week or so ago. We just put the pool in last summer (18'x52") with a Intex SWG CS8110) and a GAME SandPRO Model 8511 Filter. It worked great all last year, then this year I started getting a Code 91 on my SWG (The SWG was drained and cleaned at the end of last year). I had the pool store check my Salt level about 2 weeks ago and they said I was at 2500 so I added ~40lbs of salt, which from calculations on this site should bring me up to a little over the ideal of 3000, pool circulated water for 24 hrs and still code 91 (low salt).

    I did the vinegar cleaning (the exterior of the plates I didn't think were that bad), with the plates in the bath for about 4 hrs, and afterwards I found a small deposit remaining between one set of plates (outer and middle). A careful insertion of a long thin bladed (bread) knife removed it, trying not to scrape the plates themselves. It was soft and came out easily. It was something soft, white and about the consistency of a mud. Another vinegar cleaning just to be sure I was clean (the plates were now a dark color, as normal) and I was still getting the Code 91 error. I tried pulling the big plug that attaches to the cell and re-connecting it (in case of a bad connection) but still code 91 error. I also noticed the plug was a little wet but noting obvious on the cell (or connector that was leaking so it much be small). I then broke out the volt/amp meter to see if voltage was getting to the plug. From what I have read on the internet the way the unit determines the salt level is by measuring the current, too low and it's a low salt condition, to high and I guess to high of a salt level. There are also some internal rheostats that can be fiddled with, but since my unit is only 1 yr old I really didn't want to open it up. Unfortunately nobody online tells you what voltage/current/resistance the unit should have.

    I had the pool water tested at the local pool store and I now have 3100 salt level.

    I checked the resistance across the two plates (as measured from the connector) I got ~9M ohms (wet, pool water). That's not surprising. Also, just measuring the resistance with my leads in the water showed about the same value.

    Voltage at the plug (not connected to the cell) 13.5V

    Still a Code 91 error when I plug things back in and have pool water running through it.

    So I then broke out the portable 12v jump starter that I have for my car (one of those self contained things that you can buy at the auto parts store, it has like a 900mAh 12v battery that you can use for jump starting a car) for a portable power source to connect directly to the posts on the SWG cell (bypassing the unit itself). With water flowing, I connect the battery and bubbles appear in the stream (the cell itself is working). I only left the battery connected for about a minute, really just long enough to see bubbles coming out of the cell. I didn't want to put too much current onto the plates as I didn't know what they are rated at. I have heard other people use battery chargers to do the same (and measure the current this way as well). This makes me think it is probably a low current output issue with the unit, and hence the error code.

    I plug the unit back in and suddenly the unit starts generating bubbles (and no Code 91 error)!!! Now I don't think hooking up my portable battery really did anything but somehow my unit started working again on it's own. I also don't think it was a bad connection since I had plugged/unplugged the big black plug on the cell several times already. I also don't think it was the water on the plug, because I had dried it off before, and it was damp when it started working again. Thank goodness it started working though. I also noticed that when the unit was generating Chlorine I could now hear a fan running in the unit, I didn't notice this fan when it wasn't working.

    So, here are some numbers (which I couldn't find on the internet) from a working unit (this is for an Intex CS8110 purchased in 2011 with the Copper Ion generator(unhooked)).

    Outputs (when working and generating) at the big black plug that connects to the plates.
    Voltage 13.5V (no load)
    Current Approx 4.5A (connected to SWG cell)
    Resistance across the cell (3100 ppm salt level) Approx 9Mohms, Approx 10Mohms dry cell (it my not have been completely dry)

    I don't know if the numbers will help anybody else, but I hadn't seen anybody post them on the internet. Luckily my unit started generating on its own again. I did see the 13.5V when the unit wasn't working, but it started working before I could try measuring the current from the not working device.

  5. #5
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    Re: Intex CS8110 Salt sensor question

    BTW, The 13.5V (no load) is before the unit shuts itself down (code 91) because I don't have it hooked up to the cell, it will output the voltage for maybe 15 seconds (until the unit errors) and then error and the voltage will drop to 0V with the error.

  6. #6
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    Re: Intex CS8110 Salt sensor question

    If it is still under warranty and you have a receipt, call Intex for a replacement. If it is out of warranty or you just want to fix it, here is what I would try in order:

    1. Clean the cell with vinegar.

    2. Flip over the big plug that powers the cell (Reverse polarity).

    3. Open the case and adjust the resistors. This has worked for several people with this problem.

    4. Rewire the unit, bypassing the control unit. I had to do this to mine this year since it appeared to be working correctly (not throwing any error codes and showing 93 at the end of the cycle, but was not actually energizing the cell. My unit is a 2008 model so your wire connections may be different. I'm not an electrician, so my terminology is likely way off. There is a four post terminal under the hood of the control unit. The outer two wires (posts 1 and 4) come from the power supply and the inner two wires (posts 2 and 3) go out to the cell. I put wires 1 and 2 on post 1 and wires 3 and 4 on post 4. This bypasses the control unit and sends power directly to the cell. I also moved the fan wire to a different socket where it has constant power when the unit has power. I don't know if this part was necessary with this setup, but it shouldn't hurt. I then plugged the unit into a timer. Whenever power is supplied to the unit by the timer the cell is energized and the fan is running. It is critical that the pump be running whenever the unit has power since the flow control has been bypassed and the unit will not know to shut itself off. I'm sure someone with more knowledge of electronics could figure out a better way. There are a couple of YouTube videos showing how to do this. The sound is very poor, but the visual is pretty easy to follow.
    18'x48" Intex metal frame pool, 1600 Intex sand filer/pump combo, Intex SWCG.

  7. #7
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    Re: Intex CS8110 Salt sensor question

    Like rg said above I also "repaired" my unit that had the exact same problems. This is only what I did. I am not suggesting you do it. After unplugging the unit and removing it from service. I removed the white cover with the electronic controls by removing the 4 phillips screws at the bottom and sliding it up. Once it is raised up enough you will see 4 thick wires that connect on the left side of the circut board. Two of these wires can be traced back to the transformer( which is under a seperate gray cover) and the other two wires will go to the salt cell. Use the screw driver to remove the wires from the circut board. What I did was connect them together, connect the two wires from the transformer to the two wires going to the salt cell. It does not matter which color goes to what color. You can reverse them and it will only reverse the polarity. Make sure and use wire nuts or black tape to keep them from touching each other or anything else. Once this is done I must warn you!
    1) The controls no longer work, you will have to put the unit on a timer. Why. Because the cell is hooked up direct it will make clorine all the time when it is plugged in.
    2) you will have no more alarms, even low flow.
    3)If the water pump stops for some reason the unit will still continue to make clorine with no flow, and this is bad for several reasons.
    4) The unit will not self reverse the polarity anymore, so you will need to clean the cell more frequently.

    This will make it functional again until you can buy a new one, buy replacement parts or rewire the circut board.

    After I purchased my new unit I took another look at the one I "repaired" and was able to rewire the circut board and install a pot so I could set the desired resistance and have the unit function as normal.

    Also I would like to also add that it is my opinion that once a unit starts acting up like that it needs a new cell. Period. The mod will get it back working again but the output will be alot lower than a new cell. I saw this first hand last year. I was running the unit for 10 hrs to get my FC to where I needed it with the new unit it dropped to 6! I now have the old unit as back up.

    Mods, if this post is considered unacceptable or unsafe please delete it!

  8. #8
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    Re: Intex CS8110 Salt sensor question

    I had the error 91. I believe I tried everything on the Internet. I was resigned to returning the unit when I thought to try another outlet. It worked! I had the fiilter pump and the SWC on the same outlet. The house is older. Putting the SWC on an outlet by itself solved the problem.

  9. #9
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    Re: Intex CS8110 Salt sensor question

    Pappaprime, where exactly did you add the pot to the circuit. I have an older one I modded the heck out of new LEDs, flow sw directly contols cell relay ect. I did this because I needed longer than 12hr run times on a 20k gal pool especially when it was 110+ last year and CSI was off. I had to be able to keep up and shock when I got a agle outbreak so I went Mod happy. I have a good video of the mod but it's 5 gigs.
    20,000 gal. 32' x 17' freeform custom pool, 3ft. shallow - 8ft. deep end, Pentair Whisper flow 2.2 HP WF-6 for cleaning only, Neiko Tools USA 1 Hp pump for primary filtering job saved 25% on electricity! , Purex/Triton Nautilus FNS48 DE filter, Kill A Watt EZ to keep a eye on electrical costs wired for 120/240v, Experimenting with DIY solar heater made from 1/2" irrigation black polytubing. Spa: Beachport 5 person/350gal. , Intex Clorine Generator internally modded w/external digital timer for 8 min runs daily. Wishlist: permenant solar system, Slide (bought just need to install), Fountain, Automation, Automatic Cleaner. http://www.tftestkits.net/ http://www.poolcalculator.com/ category/pool-school/

  10. #10
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    Re: Intex CS8110 Salt sensor question

    Have the older version of the 8110 (only 2 buttons and two lights - no copper electrodes). In it's 5th year - does a great job for an inexpensive chlorinator
    Low salt issue can be caused by bad connections with the cell plug - corrosion is an issue. As mentioned, turn the plug over and it may improve things.
    Currently I have bad connection that heated up enough to discolor the plug cover - connection is fried.
    Plan is to use industrial wiring connections (guts from Weidmueller strips) to connect the wires to the cell contacts with heat shrink over top.
    Looking at the issue of auto-startup on power application - this is the ONLY weak spot for this asset.
    Will try to update later with pictures & info.

  11. #11

    Re: Intex CS8110 Salt sensor question

    Please update with pics & info. We can't get the electrical back up. Dad took a car battery charger to the outside and plugged it up. Only the generator part works - no timer or nothing
    20 x 48 Intex Ultra Frame
    Sand filter with SWG attached.
    Deck added on (05/18/2013)
    Thinking about adding more deck
    Pool steps added in - (got rid of that crappy ladder that came with Intex pool) 05/18/2013.

    "A little bit of paradise in our yard"

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