Too Much Jerking Around?

[hrustar]

Over the last week, i've tried to gain better ocntorl over my spa water. Instead, i've just introduced chaos. First it was adding borates, now Sodium Carbonate.

In the latest example, my TA was fine (75) but my PH was very low.

So, I used Sodium Carbonate (Arm & Hammer Wash Soda), applied it to the Pool Calculator spec (3 oz.) and wow, my TA and PH is now off the charts.

Is the pool calculator totally screwed up in terms of its dosing?

Makes me just want to be ignorant again and keep dropping dichlor.

[NewB@Spa]

I thought you only add Borates during your new fill unitl your CYA is 20 - 30?

[mcw53]

Over the last week, i've tried to gain better ocntorl over my spa water. Instead, i've just introduced chaos. First it was adding borates, now Sodium Carbonate.

In the latest example, my TA was fine (75) but my PH was very low.

So, I used Sodium Carbonate (Arm & Hammer Wash Soda), applied it to the Pool Calculator spec (3 oz.) and wow, my TA and PH is now off the charts.

Is the pool calculator totally screwed up in terms of its dosing?

Not sure of your spa size, but the pool calculator shows 3 counces of sodium carbonate will raise pH by 1.86 and TA by 61 ppm in a 350 gallon spa. These are HUGH adjustments. What was your original and target pH?

[hrustar]

Over the last week, i've tried to gain better ocntorl over my spa water. Instead, i've just introduced chaos. First it was adding borates, now Sodium Carbonate.

In the latest example, my TA was fine (75) but my PH was very low.

So, I used Sodium Carbonate (Arm & Hammer Wash Soda), applied it to the Pool Calculator spec (3 oz.) and wow, my TA and PH is now off the charts.

Is the pool calculator totally screwed up in terms of its dosing?

Not sure of your spa size, but the pool calculator shows 3 counces of sodium carbonate will raise pH by 1.86 and TA by 61 ppm in a 350 gallon spa. These are HUGH adjustments. What was your original and target pH?

My spa is 425 gallons. According to my taylor K2006, my PH was sub 7 and when I did the base test I need 12/13 drops. Can;t remember the actually ph reading, but I used the charts in the K2006 book to figure. As for my TA, it was around 75. But the kicker is the adjustments shot both my ph and ta way beyond predicted levels.

[bart6453]

Over the last week, i've tried to gain better ocntorl over my spa water. Instead, i've just introduced chaos. First it was adding borates, now Sodium Carbonate.

In the latest example, my TA was fine (75) but my PH was very low.

So, I used Sodium Carbonate (Arm & Hammer Wash Soda), applied it to the Pool Calculator spec (3 oz.) and wow, my TA and PH is now off the charts.

Is the pool calculator totally screwed up in terms of its dosing?

Not sure of your spa size, but the pool calculator shows 3 counces of sodium carbonate will raise pH by 1.86 and TA by 61 ppm in a 350 gallon spa. These are HUGH adjustments. What was your original and target pH?

My spa is 425 gallons. According to my taylor K2006, my PH was sub 7 and when I did the base test I need 12/13 drops. Can;t remember the actually ph reading, but I used the charts in the K2006 book to figure. As for my TA, it was around 75. But the kicker is the adjustments shot both my ph and ta way beyond predicted levels.

I always halve my additions so I don't overshoot. If I calculate having to add 1 ounce, I add a half and re-test in 30 minutes.

the only thing I dont do that on is sanitizer.

[hrustar]

Good advice based on my results thus far. Don't get me wrong, I love the Pool Calcualtor as a guide for my actions, I just take the numbers with a grain of salt now.

[chem geek]

I thought you only add Borates during your new fill unitl your CYA is 20 - 30?

You are mixing up Dichlor and Borates. It's Dichlor that you start out with to cumulatively add around 33 ppm FC which will result in around 30 ppm CYA. Borates are added as an additional pH buffer, not for CYA.

[NewB@Spa]

Told ya I was a NewB

[chem geek]

Good advice based on my results thus far. Don't get me wrong, I love the Pool Calcualtor as a guide for my actions, I just take the numbers with a grain of salt now.

Note the following stated on The Pool Calculator:

Note: pH calculations are not exact. These numbers are only suggestive of the relative magnitude of the pH change you can expect. Small changes, +-0.4, with pH between 7.2-7.8, TA around 80-120, and Borate near zero will be approximately correct. The further you go from those ranges the less these numbers will correspond to reality.

I have a spreadsheet here that does the accurate calculations, but it is not for novice users and unfortunately the pH calculations aren't simple enough to put into the pool calculator (I didn't write the latter, but helped Jason with some algorithms, though he made the approximate pH tables himself).

Note that using pH Up will increase TA as well as pH. The effects of adding chemicals section in The Pool Calculator tells you that and as mcw53 noted even The Pool Calculator predicted the pH and TA would go through the roof. You are blaming The Pool Calculator for an error it had nothing to do with. You figured out how much to add based on the base demand test and the Taylor book, not The Pool Calculator, right? Going from 7.0 to 7.5 in The Pool Calculator just says to add 1.2 ounces weight or 1.0 ounces volume of washing soda / soda ash (i.e. pH Up or Spa Up), not 3 ounces.

If I use your numbers with no Borates, then my spreadsheet says to use 1.0 ounce weight or 0.9 ounces volume and that the TA would rise to 92 ppm as a result (along with the pH rising to 7.5 from 7.0). If you had 50 ppm Borates, then 1.6 ounces weight or 1.4 ounces volume would be needed.

The source of the problem appears to be the base demand test and the Taylor book. 12-1/2 drops in 425 gallons says 2.05 * (425 / 400) * (12.5 / 10) = 2.7 ounces soda ash. Based on the Taylor book recommendation and your base demand result, the implied starting pH (assuming 50 ppm Borates in the water) is 6.75. How did your pH get so low? Are you using lots of non-chlorine shock (MPS)?

As others have noted, when adjusting pH it is better to use half the estimated amount. Normally the Taylor acid/base demand tests are reasonable, but for whatever reason they weren't correct in this case (and you added 3 ounces instead of the 2.7, though that would have only helped a little). Also, to raise the pH with no change in TA, you would simply aerate the water (i.e. run the jets). To raise the pH with half as much rise in TA as when using soda ash (Spa Up) you would use 20 Mule Team Borax instead. Basically, you don't want to use sodium carbonate (spa up) unless you really want to raise your TA substantially. Sodium carbonate is identical to adding a combination of a sodium hydroxide (lye, a pure base) and sodium bicarbonate (Alkalinity Up) so unless you really wanted to raise both pH and TA, you don't use sodium carbonate. And yes, the Taylor book refers to it, but the Taylor book doesn't tell you everything that you need -- it doesn't talk about aeration to raise pH nor about using 20 Mule Team Borax to raise pH.

Richard

[hrustar]

Good advice based on my results thus far. Don't get me wrong, I love the Pool Calcualtor as a guide for my actions, I just take the numbers with a grain of salt now.

Note the following stated on The Pool Calculator:

.You are blaming The Pool Calculator for an error it had nothing to do with. You figured out how much to add based on the base demand test and the Taylor book, not The Pool Calculator, right? Going from 7.0 to 7.5 in The Pool Calculator just says to add 1.2 ounces weight or 1.0 ounces volume of washing soda / soda ash (i.e. pH Up or Spa Up), not 3 ounces.

Richard

Actually, I used the Taylor book for a guide, and used the pool calculator's data. I'm not saying its at fault. I'll accept user error on my part. I am still new to this whole spa water thing. Please take no offense at the tool or your advice. The point of this thread was maybe i was trying to do much, too soon. Perhaps, i need to take more baby steps.