New TFTestkit and results question

[isabelo]

The last time I tested my pool water(January/February timeframe), the CH was hovering around ~200 to ~250ppm. When I got my TFTestkit refill, I immediately threw the old reagents away so as not to mix them with the new ones. But when I tested the CH last week and again today, it measured at ~425 to ~450ppm. This seems pretty drastic of a hike on measurement especially since we have not used the pool since September last year and our pool is covered with an automatic pool cover 99% of the time except for testing.

We've had some pretty heavy rains in Northern California (Bay Area) in January, but dry in February, then some rain in March - could this have caused the sudden rise in CH? Or was the older reagent not giving me correct results? The pool water is still around the vicinity of 55deg to 65deg F.

Also, the "Pool School - Recommended Levels" call for TA to be 70ppm to 90ppm for bleach. However, the chart from TFTestkits says 100ppm to 120ppm for manually chorinated pool - so which one to follow? My TA now is measuring ~125ppm (I was getting ~90 to ~100ppm using the older reagent - strange). Should I follow the Pool School recommended levels, or should I follow TFTestkits numbers?

 

[duraleigh]

Let's talk about the TA first. When you get new testing reagents, the R-0009 (the one where you count the drops), is often so fresh it gets static electricity interfenrence from the plastic bottle. The end result is the drops are usually smaller and the TA readings tend to be higher.

The solution is to wipe the dropper tip of the R-0009 with a damp cloth in between about every other drop. Ther second solution is after a couple of weeks, that static dissipates and your R-0009 acts as it should and your TA reading will likely come down.

The CH is a hard test to stay accurate. Are you using a speed stir?

 

[isabelo]

Let's talk about the TA first. When you get new testing reagents, the R-0009 (the one where you count the drops), is often so fresh it gets static electricity interfenrence from the plastic bottle. The end result is the drops are usually smaller and the TA readings tend to be higher.

The solution is to wipe the dropper tip of the R-0009 with a damp cloth in between about every other drop. Ther second solution is after a couple of weeks, that static dissipates and your R-0009 acts as it should and your TA reading will likely come down.

The CH is a hard test to stay accurate. Are you using a speed stir?

Yes, I am using a speed stir (bought it from you last ~spring).

So, to get back to the TA recommended levels, why is there a discrepancy between what the Pool School recommends and what TFTestkit recommends?

For the CH level, I just did a water change about last spring to lower down my CYA from ~80ppm to ~40ppm. Now my pool water has ~25ppm CYA. My point is that the CH level then was so low but learning from reading the forums and CH, I did not bother raising it since over time it will go up. But I did not expect it to go up this much (from as low as ~70ppm to ~450ppm) in a year with very minimal pool use and only 4 people using it.

 

[duraleigh]

Good. The speedstir is especially helpful on the CH test.

could this have caused the sudden rise in CH? Or was the older reagent not giving me correct results?

Honestly, I just don't know. CH will always have a tendency to rise but I am having trouble thinking of a scenario for that 200 PPM rise.

The CH is not dangerous at all but I would suggest you catch all the rainwater you can for your pool (even diverting a roof downspout if possible) and, importantly, closely monitor your pH keeping it not higher than 7.4 or so

 

[isabelo]

Good. The speedstir is especially helpful on the CH test.Honestly, I just don't know. CH will always have a tendency to rise but I am having trouble thinking of a scenario for that 200 PPM rise.

The CH is not dangerous at all but I would suggest you catch all the rainwater you can for your pool (even diverting a roof downspout if possible) and, importantly, closely monitor your pH keeping it not higher than 7.4 or so

Okay, I'll monitor the CH closely. I have no way of diverting rainwater.

As for the TA recommended levels, why is there is discrepancy between Pool School and TFTestkits?

 

[Texas Splash]

Not too long ago, the TFP staff scrubbed several items on the Recommended Levels chart and Poolmath Calculator for each pool type. Those adjustments were made fairly quickly to all the on-line resources, but it takes a little while longer to manufacture/publish the cards in the test kits themselves. Even though they do not match exactly at the moment, they are still within the overall parameters of TFPC and will work fine. But the on-line resources are updated closer to "real-time" values to provide the most optimal levels. The folks at TFTestkits are aware of the issue and working to update those reference cards as soon as they can. Thanks for asking and being so astute with your testing.

 

[isabelo]

Not too long ago, the TFP staff scrubbed several items on the Recommended Levels chart and Poolmath Calculator for each pool type. Those adjustments were made fairly quickly to all the on-line resources, but it takes a little while longer to manufacture/publish the cards in the test kits themselves. Even though they do not match exactly at the moment, they are still within the overall parameters of TFPC and will work fine. But the on-line resources are updated closer to "real-time" values to provide the most optimal levels. The folks at TFTestkits are aware of the issue and working to update those reference cards as soon as they can. Thanks for asking and being so astute with your testing.

Thank you Texas Splash (Pat?)