New water fill questions

Cousinvinny

Member
Apr 3, 2021
14
Tucson, Az
Hello all, getting ready to balance the new water in a 2 month old Bullfrog tub. Purged with Ahh some and got a neglidgeable amount of gunk. I'm ditching the [email protected] system and going the dichlor/bleach method. Here's the starting point:
FC-0
CYA-0
TA 150
PH 8.2ish (guessing)
CH 200
I'm thinking to start with .04 oz of dichlor according to poolmath to get some chlorine going. Does that sound right? And which should I adjust next since Ph and TA are both high. Sooo glad I found this site, PS had me going in circles!
 

5tan

Active member
Jan 9, 2021
37
Canada
Pool Size
1643
Chlorine
Liquid Chlorine
Adjust your pH first: 8.2 is high for a spa, get it down to 7.2 by adding the specified amount of dry acid per PoolMath using your spa capacity and the other numbers. Any pH reducer (most cases dry acid or muriatic acid) will also drop your TA, which is expected and desired when your TA is 150. You want your TA to sit at the lower end of 50-80, preferably 50, which will be accomplished by adding dry acid regularly. When using the spa, you will be adding dry acid regularly, because you'll see that your pH drifts upward the longer you have your jets on.

Also, the higher your TA, the faster your pH will rise. TA is basically a measure of dissolved baking soda (carbonic acid), and aeration offgasses the carbonic acid, causing increased pH. However, by adding acid to lower you pH, you will also drop TA at the same time, and can accidentally drop your TA below 50, so test every 6 hours and if your TA goes below 30, add enough baking soda (aka Alk-Up) to hit 50 per PoolMath.

When you get your pH down to 7.2 and TA down to 50, add 50ppm borates per the PoolMath amount of 100% boric acid (e.g. SpaGuard Optimizer) to "lock in" your pH, meaning the borates will act as a pH buffer and will greatly slow your pH rise from aeration. The borates help you use less pH reducer (aka acid) per time unit of aeration to maintain pH in the normal range of 7.2-7.6. Don't add acid unless your pH hits 7.9 or higher, and when that happens, shoot for 7.6 as the corrective amount of acid per PoolMath. With 50ppm borates, you'll see that your pH tends to stay in the 7.6-7.8 range for a long time before going higher, whereas without borates, your pH will go to 7.9-8.2 a lot faster, pretty much after every session.

From a fresh fill, you always want to maintain an FC level of at least 3ppm absolute minimum to inhibit bacteria growth, but you can shoot for 6-10ppm as the daily amount. Use the bottom part of PoolMath (where you can enter any amount of any substance) to tell you how much diclor you need to reach 20ppm CYA given your spa capacity, should be in the 60-70g ballpark depending on spa capacity.

When you've added enough dichlor to reach 20ppm CYA, then it's easy flying from there: switch to pool chlorine to maintain your daily FC level, add dry acid whenever your pH hits 7.9, and "shock" to 10ppm FC weekly or after heavy bather load. After 3-4 months, purge with Ahhsome and do it all over again. Don't forget to scrub behind those Bullfrog JetPaks with Ahhsome+superchlorinated water!
 

DanF

Silver Supporter
Mar 17, 2019
391
Chandler, AZ
Pool Size
12500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Solid advice @5tan but wondering why you only recommend dry MA versus liquid MA. Any downside to liquid MA, other than the handling of it?
 

DanF

Silver Supporter
Mar 17, 2019
391
Chandler, AZ
Pool Size
12500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
I'm thinking to start with .04 oz of dichlor according to poolmath to get some chlorine going. Does that sound right?
I think you want 0.4 ounces, not .04. 0.4 ounces will provide about 5 ppm FC (and 4.4 ppm CYA). It will also lower your pH as well.
 

5tan

Active member
Jan 9, 2021
37
Canada
Pool Size
1643
Chlorine
Liquid Chlorine
No downside to muriatic aka hydrochloric acid, aside from much trickier handling/dilution/ventilation. You'll want wrap around goggles, elbow length rubber gloves, and you'll not want to be pouring this in your house - you'll need plenty of ventilation, but also not be pouring into the wind outside either. Dry acid is much, much safer for the average person to use.

The Bullfrog owner's manual specifically says using muriatic acid will void the warranty, likely because it is easier for the average person to mishandle, i.e. pouring a non-diluted amount into a specific area and having the spa parts like the heater and pumps exposed to excessively low pH.

If you can dilute it and broadcast it over as much water surface as possible, and keep it away from all metal parts (visible and non-visible: jet ports, filter intakes, pump intakes, etc), then it should be fine. However, in a small spa, it can be tricky to avoid sucking in the low pH water into a pump or heater intake, and the low pH water will not be good for your pump or heater.

If you have a topical/dermal allergy to sulphites or sulfates, and/or if you want to keep your TDS down, replacing dry acid (sodium bisulfate) with muriatic acid can keep sodium and sulfates out of the water.
 
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Cousinvinny

Member
Apr 3, 2021
14
Tucson, Az
Adjust your pH first: 8.2 is high for a spa, get it down to 7.2 by adding the specified amount of dry acid per PoolMath using your spa capacity and the other numbers. Any pH reducer (most cases dry acid or muriatic acid) will also drop your TA, which is expected and desired when your TA is 150. You want your TA to sit at the lower end of 50-80, preferably 50, which will be accomplished by adding dry acid regularly. When using the spa, you will be adding dry acid regularly, because you'll see that your pH drifts upward the longer you have your jets on.

Also, the higher your TA, the faster your pH will rise. TA is basically a measure of dissolved baking soda (carbonic acid), and aeration offgasses the carbonic acid, causing increased pH. However, by adding acid to lower you pH, you will also drop TA at the same time, and can accidentally drop your TA below 50, so test every 6 hours and if your TA goes below 30, add enough baking soda (aka Alk-Up) to hit 50 per PoolMath.

When you get your pH down to 7.2 and TA down to 50, add 50ppm borates per the PoolMath amount of 100% boric acid (e.g. SpaGuard Optimizer) to "lock in" your pH, meaning the borates will act as a pH buffer and will greatly slow your pH rise from aeration. The borates help you use less pH reducer (aka acid) per time unit of aeration to maintain pH in the normal range of 7.2-7.6. Don't add acid unless your pH hits 7.9 or higher, and when that happens, shoot for 7.6 as the corrective amount of acid per PoolMath. With 50ppm borates, you'll see that your pH tends to stay in the 7.6-7.8 range for a long time before going higher, whereas without borates, your pH will go to 7.9-8.2 a lot faster, pretty much after every session.

From a fresh fill, you always want to maintain an FC level of at least 3ppm absolute minimum to inhibit bacteria growth, but you can shoot for 6-10ppm as the daily amount. Use the bottom part of PoolMath (where you can enter any amount of any substance) to tell you how much diclor you need to reach 20ppm CYA given your spa capacity, should be in the 60-70g ballpark depending on spa capacity.

When you've added enough dichlor to reach 20ppm CYA, then it's easy flying from there: switch to pool chlorine to maintain your daily FC level, add dry acid whenever your pH hits 7.9, and "shock" to 10ppm FC weekly or after heavy bather load. After 3-4 months, purge with Ahhsome and do it all over again. Don't forget to scrub behind those Bullfrog JetPaks with Ahhsome+superchlorinated water!
5tan, thank you for the detailed explanation. So far TA adjusted down to 60, PH at 7.5 FC at 4.5ish with 1.5 ounces of Dichlor added. Since my test kit starts CYA at 30, how do I measure it below that? Do I just aproximate according to PM that CYA is at 17 since 1.5 ounces of Dichlor added so far?
 

5tan

Active member
Jan 9, 2021
37
Canada
Pool Size
1643
Chlorine
Liquid Chlorine
No need to measure CYA directly, just assume you're starting at zero since it's a fresh fill, and use PoolMath to add up the CYA. For me, I needed a total of 65g dichlor to reach 20 CYA.

It is also good practice (and specified in the Bullfrog Owner's Manual) to superchlorinate to 10ppm upon a fresh fill, and I needed 30g dichlor to hit 10ppm. I tested every 24hrs and added enough dichlor to maintain 6ppm FC over the next few days. As soon as I hit 65-70g total dichlor added, I switched over to liquid pool chlorine.
 
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dan1333

Active member
Nov 1, 2020
25
Orange, CA
Is muriatic acid that terrible? I got the half strength to avoid some of the issues (and with hot tubs we're not dealing with huge quantities anyway so shouldn't we always be using the half strength version?). I haven't stuck my face in it and gotten a lungful but I haven't noticed any noticeable fumes. When pouring I sometimes had a drop go on my hand but I just dip it in the hot tub and it's been fine.

Should I really be wearing a respirator and big giggles and elbow length gloves???
 

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5tan

Active member
Jan 9, 2021
37
Canada
Pool Size
1643
Chlorine
Liquid Chlorine
The 15.7% would definitely be much easier to work with than the usual full strength commercial grade 31.45%, and as such, the PPE requirements are much lower. The 15.7% is not readily available in some or many geographies - for example, in my area, when I last looked, the various stores carried only the 31.45%. When my current supply of dry acid runs out, I'll take a good hard look for the 15.7%.
 

A.O.

Well-known member
Apr 12, 2016
310
Kershaw, South Carolina
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Is muriatic acid that terrible? I got the half strength to avoid some of the issues (and with hot tubs we're not dealing with huge quantities anyway so shouldn't we always be using the half strength version?). I haven't stuck my face in it and gotten a lungful but I haven't noticed any noticeable fumes. When pouring I sometimes had a drop go on my hand but I just dip it in the hot tub and it's been fine.

Should I really be wearing a respirator and big giggles and elbow length gloves???
Sounds to me like he is wildly overthinking things, I'm normally wearing nothing more than my swimsuit when adding MA, I use the containers below, not much pouring (other than into the tub) which reduces or pretty much eliminates any mishaps. I use my tub twice a day and rarely need more than 1/4 oz twice a week of MA.

IMG_5082.JPG
 
May 15, 2021
6
Kirkwood
Sounds to me like he is wildly overthinking things, I'm normally wearing nothing more than my swimsuit when adding MA, I use the containers below, not much pouring (other than into the tub) which reduces or pretty much eliminates any mishaps. I use my tub twice a day and rarely need more than 1/4 oz twice a week of MA.

View attachment 326640
Okay, those "perfect pour" bottles are an amazing idea. Tired of that cheap measuring cup. Thank you!
 
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