Questions For Next New Water Fill Using Dichlor Then Bleach Method

[Venams]

I thought I had the system down but I added too much Muriatic this fill which resulted in PH way too low.

I then got the tub water balanced. but shot PH way too high after that by adding 3 cups of Borax. I didn't realize (until after reading threads on this forum) that you can't add all the Borax at once.

So questions for next time to make it easier and safer.

So my 2 options:

1) Can I just add the 3 cups borax (abour 450 gallon tub) right after filling and while adding the Muriatic to bring the TA/PH down? This would avoid shooting PH high again by adding Borax once the TA/PH is balanced like I did above?

2) if answer to above is NO then I'm thinking of dumping the Borax and investing in Boric Acid (since it's supposed to be PH neutral) and just balancing the tub to bring TA/PH down with Muriatic and then finishing off with the Boric Acid? The last step of adding the Boric Acid shouldn't affect the TA/PH once established right?

I just want to get this down so I don't accidentally ruin the tub on the next fill

[chem geek]

Boric acid is only slightly acidic so adding 50 ppm would typically only drop the pH from 7.5 to 7.2. It will have minimal effect on TA, having it rise by around 5 ppm when the pH is near 7.5.

If you are trying to lower the TA because it's too high from fill water, you do that by adding acid and aerating. You do NOT do that by adding any Borax.

If you are adding Borax to add 50 ppm borates, then after you first lower the TA (see above) then you would alternately add borax and acid to the tub splitting up the total dosage into thirds or fourths.

[Venams]

Thanks Chem Geek. But can't I eliminate the added tasks of multiple doses using Borax/Muriatic by just substituting with Boric Acid?

[Venams]

OK so my new tub will be roughly 550 gallons.

I did some measurements on my tap water to get a ballpark of how much Muriatic I will have to add on a new fill. I was going to plug that in to the POOL CALCULATOR to get a ballpark amount but the it's showing add 0 Muriatic Acid. I entered 325ppm TA now with Target of 75ppm with PH now of 7.5 and Target of 7.5 / What am I doing wrong?

TAP WATER:

TA = 325ppm

PH = 7.5

[chem geek]

Yes, that's the point of using boric acid instead of 20 Mule Team Borax and separate acid. With boric acid that's all you add. You probably don't need to adjust pH since it will slowly rise and it only drops some when you add the boric acid as I had indicated.

The calculator will not tell you how much acid you have to add to lower the TA since you don't add it all at once. You instead do the Lowering Total Alkalinity procedure that involves lowering the pH, aerating, then adding acid to lower the pH back down since the acid addition lowers both pH and TA while the aeration only raises the pH (due to carbon dioxide outgassing) with no change in TA.

[Greenhorn]

I found boric acid at my local hardware store. It was sold as cockroach killer, went by the name "Flute", or something like that. Would it be wise to use this? It was cheap also, at $5.50 for a pound.

chem geek, could you link some other sites that sell boric acid here. I know I ran across them in my readings, but I couldn't find them again.

[Venams]

 

Yes, that's the point of using boric acid instead of 20 Mule Team Borax and separate acid. With boric acid that's all you add. You probably don't need to adjust pH since it will slowly rise and it only drops some when you add the boric acid as I had indicated.

The calculator will not tell you how much acid you have to add to lower the TA since you don't add it all at once. You instead do the Lowering Total Alkalinity procedure that involves lowering the pH, aerating, then adding acid to lower the pH back down since the acid addition lowers both pH and TA while the aeration only raises the pH (due to carbon dioxide outgassing) with no change in TA.

 

How or what can I reference to determine the ratio of how much dry acid (by ounce) is needed to drop TA by X amount of ppm in a 550 gallon tub?

[chem geek]

If the ingredients of the cockroach killer say something very near 100% boric acid, then it should be OK to use. However, to be safe, you can get the most certainly correct stuff at DudaDiesel, The Chemistry Store, or only for large sizes (so mostly for pools), AAA Chemicals.

It takes 1.9 ounces weight (around 1-1/4 fluid ounces volume) of dry acid to lower the TA by 10 ppm in 550 gallons. You can see this in The Pool Calculator in the lower section called "Effects of adding chemicals" assuming you've set your water volume properly at the top of the page. Of course if you are lowering the TA a lot you don't add all the acid at once since it would lower the pH too much. You follow the Lowering TA procedure I linked to.

[Venams]

Thanks Chem Geek!

[Venams]

Chem Geek, one last question.

I've been using a product called Metal-X to help sequester the high minerals in our city water to prevent scaling etc.

I use about 14oz of this product per new fill.

Is it OK to continue to use as I have done in the past and will this affect any of my readings (TA, PH, CH, FC, Borate)?

[chem geek]

Unless your city water is from wells, it usually won't have iron in it for which you'd use a metal sequestrant to prevent scaling. Are you saying that the city water is high in CH? You can measure that to see if that's true. It probably won't affect any readings since the CH test likely measures the calcium bound to the sequestrant (since it's an equilibrium so is probably released in the time of the test), but it should prevent scaling. Unless your CH is well above 150 ppm, I wouldn't worry about that. We usually recommend raising the CH to 120-150 ppm to prevent foaming anyway.

[Venams]

Chem Geek. Our city water is taken from wells so it is fairly high in Iron and other minerals.

CH from my tap came in around 70ppm. I didn't add anything to boost the CH levels and just balance the TA/PH and added the Borax. I was just wondering about my test results being off because of the Metal-X sequestrant.

[chem geek]

OK then. Yes, the metal sequestrant is needed for handling the iron in the fill water. There are some other ways people try and deal with it by using batting and shocking with bleach to raise the pH and chlorine levels which precipitates iron oxide, but I would think that would risk staining as well. There are also greensand iron filters and ion exchange filters that can remove the metal ions.

Anyway, the Metal-X shouldn't affect the standard test results.