Two stabilizer recommendations which way do we go?

[poolnorthernva]

Hi all.
We are on week 5 with water. We added salt last Thursday. Started the swg on Saturday. The documentation for the Intellichlor recommends cya between 30 to 50. The TFP method suggests 70 to 80. We are adding cya and expect our levels to be around 50. We will do a measurement again this weekend to confirm.

We are confused about what our cya goal should be. What are your suggestions and why.

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[Texas Splash]

Not having enough CYA in the water can create problems like high acid demand, algae outbreaks, cloudy water, or early cell failure. The higher CYA also works to protect what would typically be your low FC level generated by the SWG. Manually-fed pools require a bit more FC which is relatively easy to do - simply pour or adjust the auto-pump to dispense.
Pool School - Salt Water Chlorine Generators
Pool School - Water Balance for SWGs
Of course also continue to watch your pH and TA closely to protect the hardware in your SWG.

 

[Divin Dave]

Hi,
TFP makes its recommendation with one of the goals to extend the life of the cell. They are expensive to replace and we want to extend their life if possible.

If the CYA is kept in the 70-80 range, then there will be less loss of FC to UV from the sun and also, the FC recommendation can be a bit lower than a manually dosed pool, because the SWG can add the chlorine by running a few short times over course of a day, rather than adding a days worth all at one time. (you can run the SWG and produce the chlorine all at once, but is inefficient way to operate the salt cell).

If the CYA is 30-50, there will be more FC loss to UV, which means the SWG will need to run for longer period of time or at a higher % output to replenish it and maintain the recommended FC level.

The net result is that keeping your CYA a bit higher will extend the life of the SWG cell considerably. There are many folks here on TFP who are going on 6,7,8 or more years on the same cell, and the manufacturers regularly state that their life expectency is 3 to 5.

As with almost all things there is a downside to keeping a higher CYA. The possible downside to maintaining CYA at higher level, is that if the adequate FC/CYA level isnt maintained, an algae bloom could occur. If this happens, then clearing the algae will be a more difficult task and take more liquid chlorine to do it because of the higher CYA.

However we feel the risk is acceptable in that algae blooms most often occur in pool which are chlorinated manually. Folks go out of town or maybe just get lazy and they dont maintain appropriate FC. The SWG doesnt go on vacation and doesnt get lazy, and adds chlorine regularly, so an algae bloom is much less likely to happen.