SWG ORP and pool blankets

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D

Dazzamc

0
Oct 4, 2016
18
Western Australia
Hi all,

Just after some thoughts about ORP levels and how they can be affected by the installation of a pool blanket.

After 3 months I have finally got my ORP set so it returns a chlorine reading of between 1.5 - 2 ppm with the pool blanket off. I'm about to fire up my heat pump for the swimming season and will routinely have the blanket on so the heap pump doesn't work over time.

My question is; what can I expect the chlorine level to do once the blanket is on with the ORP unchanged.

The pump is set to 28deg C and the ORP is set to 550.

Should I lower the ORP?

Thanks in advance.

Sent from my SM-T810 using Tapatalk
 
Your FC will increase with less UV extinction because of the cover. In a non-ORP controlled pool, one would simply dial back their SWG or decrease bleach additions to compensate. The problem with ORP (and one of the reasons why we don't advocate it's use as a positive feedback control) is that there is no telling what the ORP voltage will do. Normally, one would expect and increase in the ORP voltage with an increase FC (theoretically it should be ~18mV per doubling of FC) but most probes vary quite a lot in their output. So, unless you do the work to recalibrate your ORP probe output versus FC with a cover on, there's just no way to know what will happen. If your probe sees no change in ORP and thus keeps the chlorinator output constant, then you your FC will increase due to the cover reducing FC loss.
 
I think I'll adjust the setting down slightly to see what happens. Although I have the setting at 550 at the moment the ORP reading is at 660 which is giving me chlorine reading of between 1.5 and 2 ppm.

I'm in Perth Western Australia and spring hasn't sprung yet (**** it) so UV levels haven't been that high. Expecting that to change in the next week or two which will probable mean another change.

What reading do suggest I use on the SWG. I can change the reading to reflect low, good or high but hats about it?


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I don't know what type of SWG you have (please put your equipment in your signature line when you get a chance). Most folks here in the US don't bother with ORP control and simply operate their SWG's in a duty cycle mode - you adjust the output % setting which is just how much of a specific time period (typically 1 hour) that the SWG is ON for. For the typical outdoor, residential pool that is more than sufficient at keeping the FC at a particular level since most residential pool use about 2-4ppm FC per day.

If your SWG output is tightly integrated to an ORP probe, then there may be no way to adjust the output independent of the ORP measurement. Please specify your equipment when you can and we can look into it further.
 
Let me know how it goes with you. I am going to ORP control next spring (in US) and have a autocover, so would be interested in your results. My SWG will currently automatically adjust the output based on water temp, but of course does not know when cover is closed, so if I close to try and keep heat in (or if rainy day) then the FCL will jump up because of lack of direct sun. So hoping that ORP control will help with that.
 
Will do Gary.

I'm still trying to get my head around this whole ORP thing. When I was sold on the idea of having an auto chlorinator/PH'er I thought I just set the ORP and the sensor does the rest. Lowering or increasing the chlorine production to keep it at a set level irrespective of UV, covers etc. My local pool shop informs me nothing good be further from the truth. Apparently, the ORP needs to be adjusted constantly. Unsure why.

I'm going to call the manufacturer on Monday and get the low down.

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There are some using it without major issues. From my reading/talks told must have cyn at low level (ie. 20-30).

dradam keeps his cover most of time. He feels this keeps the temps more stable and as a result the ORP / FC to be more stable. He has written an article (PDF) of his experience with automation and his SWG - here.
 
A good read. Love when users post experiences. Makes it a lot easier for pool noobs like me.

I have just covered my pool and fired it up my heater ready for the swim season in Western Australia. Lowered my ORP a touch to compensate for the reduction in UV.

My TC is sitting at about 3ppm so will monitor and post result this time next week.

30K LT BRP fibreglass pool, Astral ZX150 cartridge filter, Astral EVO320 varible speed pump, Astral Viron Ai EQ3 SWG, Astral 9KW BPA400 heat pump, Dolphin DB1 robotic cleaner
 
I think I have found the problem with my SWG and it not producing chlorine. I checked the FC this morning at 2.8 after it returned a reading of 3.6 yesterday morning. I test this afternoon returned a reading of 2.2. The ORP reading was at 670 with a zero output even though we had 6 kids and 2 adults in the pool most of the day.

So, I started playing with the settings on the Astral SWG and found the calibration setting. As I had the ORP set at 520 I recalibrated the ORP to 510 and low and behold it's starts producing chlorine at +8% until it reached 520 then stopped.

To confirm, I'll test the pool tomorrow afternoon and fingers crossed my FC reading will be at about 3.5ppm.

It appears as the though the handover contractor didn't calibrate the the sensors as I had to recalibrate the PH sensor also (he also didn't test or put any chemicals in the pool the pool :(





30K LT BRP fibreglass pool, Astral ZX150 cartridge filter, Astral EVO320 varible speed pump, Astral Viron Ai EQ3 SWG, Astral 9KW BPA400 heat pump, Dolphin DB1 robotic cleaner
 
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