ORP 580 and FC 4.2 and TC 4.3 help

[Lamby2244]

Endpoint titration testing is the gold standard and will yield the best results. Palintest (depending on the model) are solid machines but they need maintenance, can fall out of calibration and in a perfect world you back it up with an FAS-DPD titration kit.

Do you have check standards for your palintest? If not get some if you want to use it. The standards will allow you to verify if it’s fallen out of calibration. Clean you tubes well with alcohol and if they are scratched etc, replace them. You can send your Palintest in for verification of accuracy and it can be adjusted/recalibrated. It costs some $$ but worth it if you’re in doubt of the kits accuracy.

As for your ORP reading being off, if the probes have been cleaned and you’ve tried new probes, I’d raise the set point of PH up to 7.5. In theory this should allow for an ORP in the mid 700’s with a relative FC reading in the 3’s. As the water warms your ORP readings will likely shift as well. You can run a CYA up to around 30 without terrible interference with the probes.

This chart may help you with a relative understanding of where your ORP should land relative to FC at a given PH. Due to the many variables involved, this chart will get you in the ballpark but will never be perfect. You should always rely on a known good test kit and calibrate/set your probes/system to those readings. Frequent testing and calibration to the test kit is key.

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This is amazingly helpful- thank you. Am playing with my new Taylor k2006 set and will be going with this in future. I will also raise the set point on Ph and see what happens. Thanks for the explanation

 

[Lamby2244]

What are the age of the reagents? Are they discolored or have any brown speckles on them? That’s indicative of them going bad…..they can and will go bad in the foil bubble packs. I’ve seen it too often.

The reagents are less than 6 months and are in good condition. I look after my photometer well but the new Taylor kit takes away the reliance on kit…. So will use that

 

[AUSpool]

This is amazingly helpful- thank you. Am playing with my new Taylor k2006 set and will be going with this in future. I will also raise the set point on Ph and see what happens. Thanks for the explanation

The Taylor SpeedStir, Smart Stir or a portable magnetic stirrer will make the titration tests easier and more reliable. I would never be without one. Amazon or eBay will be your best shot. It should come with a mixing bar and the cylinder. I use SpeedStir which battery operated and has a light. I think the Smart Stir is the same.

A 10ml sample for the FAS/DPD is all you need and will save on reagents. 25ml for the alkalinity. 10ml for CH.

I shocked the pool - I haven’t used it through the winter so that seemed to work and because it’s very sunny here the chlorine levels dropped back to normal quickly.

Good choice, way better than an algacide.

I’ve never needed to shock my pools. I keep my FC at roughly 10% of my CyA, 7/70 through summer and 5/50 over winter. It is a bit of a leap of faith at first but it really works. Understanding the FC/CyA relationship is the key and it’s backed by sound chemical science. Although high CyA will wreak havoc with your orp system. Try 3ppmFC/30ppmCyA and see how that works with the ORP. See;

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

And when you consistently run a stable FC to CyA ratio there is no need to push your pH so low. You can easily run the pH between 7.6-7.8 or even 8.0. At a higher pH you’ll use way less acid as the pH becomes more stable on its own. Obviously with orp control you’ll want to pick a value and maintain that with your controller. Try a pH of 7.6 a go.