False low salt readings....

[Sully]

I recently bought my house and am still learning about maintaining the pool. In particular I am having an issue with the chlorinator. It is giving me a considerably lower salt reading than what I have been told it is at two different pool stores. They have told me my levels are at 3200 while the cell is reading much lower. I did notice while playing with it today that my salt reading jumped up to it's true level when I turned on the second pump for the spa jets. Is it possible that there is too low flow going through the cell without the second pump on to get an accurate reading? There is what I believe is a check valve right before the flow meter and cell, could this be sticking and not allowing proper flow?

My system is an Aqua Logic AQL-P-4, The cell is a T-15 (pool is approx. 26,000 gallons),

 

[Bama Rambler]

What's your filter pressure reading with just the main pump running?
What's the flow out of the return(s) when just the main pump is running?

 

[Sully]

Thanks for the fast reply Bama. The filter pressure is reading 25 psi. Not sure what you mean by the returns.

 

[Bama Rambler]

What type filter is it.

With that high a filter pressure, it sounds like the filter needs cleaning. Your filter pressure shouldn't run that high.
By the return I mean the nozzle where the water flows back into the pool.

 

[Sully]

I actually have been cleaning the filter a couple of times a day because I had off the chart phosphate levels. Does the filter need cleaning beyond just spraying it out with the hose. Sorry if this is basic stuff but it's all new to me.

 

[Bama Rambler]

What's the pressure right after you clean it?

 

[Aquatica]

sounds like low flow. we installed an ecostar pump and it was running at 700rpm and we got a low salt reading. we increased to 1,500rpm and salt reading went back up where it was before the install. so it was a low flow problem. I guess the cell needs a certain flow rate to read proper salt level and to function properly.

 

[Sully]

Pressure is pretty much the same right after cleaning. I did pull the filter all together and ran the system and the pressure was only about 6-8 psi. If it is a pressure issue at the cell could it be the check valve right before it. It seems to fix the salt readings by just turning on the spa pump for a minute and there isn't a problem again until after the system is off for a little while.

 

[Bama Rambler]

Can you post a picture of the equipment?

It could be the check valve, but the symptoms are odd for that to be the case.

If your pressure without the filter is almost 20 psi less than with, I believe (as I have from the start) that your problem is with filter. Unless you took the check valve out with the filter, it's not the check valve.

 

[Sully]

I've actually run the system without the filter in. Was fine initially but again once the system was off overnight the salt readings were low (2100) when it restarted. Turned on the spa pump and immediately it jumped back up to 3100.