Fixing Error Code 91 on the Intex 8110 Salt Water Generator
filed in hacks, hardware on Sep.13, 2011
This post describes my fix for the error code 91 – low salt – I just wish I had taken photos of the plates before cleaning them. I will add those next time I do this. And my apologies for the length of this post – I never have been able to be short and sweet, lol.
We bought one of these Intex Salt Water Generators (SWG) Model 8110 about 2 years ago. Works great! The only real complaint I have is that if the power goes out, this thing loses all it’s settings and has to be reprogrammed.
Why do so many devices that have clocks, need programming, etc not have a 9V battery backup to save that information? Our Cuisinart coffee pot is the same way (no coffee in the morning if the power goes out during the night).
How much do they save by leaving that circuit out? Does that 15 cents (a pick a number guess) worth of additional electronics really make a difference to these companies bottom line? They don’t even have to include the battery – we all got used to the “batteries not included” idea years ago.
I think all product design engineers and the people who market the product should have to use these things for at least a month before they finalize the design – but, I digress, that’s another soapbox.
There are a few sites out there on the internet spreading some misinformation (like eHow) about Code 91 – low salt. They recommend taking the device at it’s word and just add more salt – that rarely cures this issue. And once the real issue is cured, you will likely get the opposite error of too much salt.
The proper thing to do is to test your pool water for salinity – take a sample to your pool dealer, or buy some salinity test strips and do it yourself.
Anyway – this Intex 8110 SWG has worked great and provided us with a crystal clear pool for 2 years. This year we started having issues with the infamous error code 91 – low salt. So, I tested the water – nope, it’s got plenty of salt.
While I’m on the subject – if you have not read the wealth of information at TroubleFreePool.com then you are missing out. They have a very simple and very effective method (the BBB method) of maintaining your pool water chemistry. It’s cheaper, easier, safer, and uses less chemicals than the potentially hazardous chemicals that your pool store says you need.
With the info on that site and the related poolcalculator.com site, it’s very easy to maintain your pool with stuff you buy at the grocery store – muratic acid, baking soda, bleach (of course if you have an Intex SWG, you don’t need bleach except maybe for shocking). They also make a top notch pool chemistry test kit – not real cheap but very thorough and well worth the investment IMO.
DISCLOSURE: I am not affiliated with those sites (other than being a forum member at trouble free pool) – and I get no compensation from them or from you clicking those links etc – it’s just good info that I am happy to share – I’m glad I made the switch to the BBB method.
But that’s more digression – back to the error code issue …
The most likely cause of the error code 91 is a salty looking crusty crud buildup on one or both ends of the electrolytic plates. That buildup changes the resistance between the plates – and the device uses a range of resistance values to determine the salinity of the water. Since the resistance has been changed, the device “thinks” (used very loosely) the water does not have enough salt.
So I recommend you disconnect the unit and look at the electrolytic plates inside – look through the long square chamber where the hoses are attached. If you have that crusty crud buildup on the plates, the steps that follow will solve that issue.
I don’t know (or care really) why the crusty crud builds up on the plates or even what it is – it looks like salt, even kind of like the white crusty stuff that gets on car battery posts sometimes.
The fix is to remove that crusty crud. Don’t use anything metal, or a brush or anything abrasive – the electrolytic plates have a very thin coating of a special metal (titanium I think) that is needed to do the electrolysis.
What we did was to tightly cap one end of the chamber using the cap that came with the SWG – I’m real glad I kept that seemingly useless (at the time) piece of plastic. Then turn the SWG with the capped end down and fill the chamber with an acid.
The owner’s manual says to use vinegar – I did not try that. If I were going to use vinegar, I’d use white vinegar full strength.
Any acid should do the trick – vinegar, Coke, 7 Up, muratic – some will just do it faster. I don’t really recommend using Coke or 7 Up – I just know that is what we used to use on car battery posts that got cruddy.
If you’re a pool owner, then you already (or should) have some muratic acid lying around, and that is what I used. But I didn’t want to use it full strength for fear of eating up something important (like my fingers, lol). I filled the chamber about three quarters full of water and then added the muratic acid to top it off.
SAFETY WARNING: Always add Acid -> Water, NEVER reverse that to Water -> Acid. Adding water to acid will cause a violent reaction causing the acid to erupt in an acidic burning spray. Wear Eye Protection please! Just remember the old A&W root beer you used to get when you were a kid – that’s the correct order – A into W.
Once you add the acid of your choice, you will notice lots of bubbling going on in the chamber. I think the bubbles are hydrogen, but not knowing what the crusty crud is to start with, I have no way to determine what the chemical reaction is so I don’t know that for sure – but you probably shouldn’t smoke around this thing just in case it is.
Let it sit a while, checking it occasionally, we’re waiting on the bubbles to stop. It took ours about 2 hours and during that time I added a bit more acid a few times. After it seemed to be completed, I dumped the water/acid mix and did it again – the second round got a few more bubbles right at first, but it stopped in about 15 minutes.
Visual inspection showed that 99% of the crusty crud was gone – I washed the remaining remnants off with a garden hose sprayer.
That’s all you have to do solve the error code 91 on the Intex 8110 Salt Water Generator if it’s caused by the crusty crud buildup on the plates. We’ve done it once in 2 years, but now that will be a part of our annual pool maintenance.
As a footnote – this particular version of the code 91 problem is caused partially by the lack of battery backup mentioned above – it’s a design flaw. According to some forums posts, one of the items stored in memory is hours of run time – and this device is “smart” enough (again, used loosely) to change the polarity on the electrolytic plates every 20 hours in an effort to “self clean” – but when it loses it’s memory due to it being turned off, or a power loss (without the aforementioned missing battery backup), it has to start remembering again.
If the device never reaches that 20 hour counter, it never reverse polarity. The idea of “self cleaning” is grand, but if it can’t remember, it can’t do it – it reminds me of Ellen DeGeneres’ character in “Finding Nemo”.
I’ve read that you can reverse the polarity manually by removing the wide black plug from the top of the SWG, turn it over and plug it back in. I can’t verify that as I didn’t try it. I wanted to visually inspect the plates and doing it this way let me verify that they were completely cleaned.
MORE DISCLAIMER: Do this at your own risk. I have described the process I used – but that was only yesterday, so I have no idea of any possible long term effects of doing things this way. I will update this post if any arise.
In the end, I pretty much followed the owner’s manual except I used a diluted muratic acid solution instead of vinegar.
All the other information shared is stuff I gleaned from reading the limited info available on the Intex website and on various pool forums on the web and I cannot attest to the validity of any of it.
of course – YMMV – Good Luck!!
