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Hello, I am new here but I possibly have something to add, I worked as a manager at a HS dealer for 6 years and probably sold the same model "spa" you have. As I remember the red light would start blinking for several reasons for instance your circulation pump may have a little bit of crusty build up from sitting and the impeller may not be turning so you have no water flowing through the heating element ant this trips your high limit thermistor, or you could have very clogged filters paticularly a clogged filter on the grey standpipe will inhibit the water flow and cause the same result, both of these could cause a blinking red light and both are pretty easy fixes compared to replacing a heater, I hope you went through some diagnostic questoning with a service tech before they just said you need a heater and sold you an expensive part. During my time with HS I dont think I ever had a customer need the control panel replaced, I believe it was call the IQ 2020 at the time and the IQ 2000 before that, but it wasent uncommon for the thermistors to go bad I seem to remember a year where they had a bad batch and we were replaceing them left and right for a time.
if I am not mistaken given that your tub is more than 7 years old you probably have the Silent Flo 5000 citculation pump and that pump dosent have a shaft driven impeller so if you take the top off of the pump the impeller is just kinda sitting there in a stainless steel cup with the top containing the other half of this "cup" and the whole thing is sealed with 1 large O ring seal taking this apart and cleaning it should be an easy job.lol but I have to stress that I have been out of the business for some time now and I think there are great resources on the web for finding parts and breakdown diagrams for this spa and I think you should also look at those diagrams before you take anything apart.
you know I am not sure what the forum rules are for posting links to businesses so I would just say if you google something like hot spring spa parts you will quickly find the type of sites I am talking about. I still hope you had a protracted discussion with the rep that told you it was a heater. I have seen the filters clogged by well water the first week of use and even if you dont have well water Baquacil products work differently than chlorine does the sanatizer in Baquacil acts more like soap rather than chlorine/bromine which are oxiders this means that there are billions of exploded bacterial bodies floating around in the spa water, now your HS spa has 3 filters so they will filter these bodies trapping them in the filter but this also means they are clogging your filter. Baquacil does have a shock (hydrogen peroxide) that will assist in oxidizing out those bodies but IMO not as well as chlorine/bromine. Being that your filters are the origional filters and they are more than 7 years old I think thats the first place to look after you have established that the circulation pump is working properly. I am sure you will find lots of opinions on this site about sanatizers and I am not trying to say anything bad about baquacil products you just have to clean your filters a bit more often IMO.notice I am saying IMO as I am sure others would disagree lol in fact reading through some of these discussions I wonder how many of these guys are just industruy professionals skillfully promoting their products.
I've seen stuff to soak them with at the spa shops and I guess I'll buy some. Without question I wasn't cleaning them enough when the tub was running. Stupid beginners mistake on my part.
If the ready light is flashing, it means that there is an issue with the control thermistor ('temp sensor') which is easy to replace and not real expensive. If you do one, do both. If BOTH lights are flashing it means a problem with the circ pump itself, or a complete air lock of the circ pump.More thoughts - Baqua has plugged up the circ pump and circ plumbing on many of our customer's tubs over the years. It can be cleaned by snaking it out. I put a small patch of cloth in the end of my electrician's snake and put it into the 3/4" plumbing starting right at the wall of the motor compartment. That line runs a circle around the base of the foot well area, and then ends at the floor drain. If you fill the tub just two or three inches over the drain fitting, water will run out and flush the goo you are breaking loose with the snake. HTH