Scale Problem

Jump to latest Follow Reply
texasbrew

texasbrew

0
LifeTime Supporter
Aug 3, 2007
51
Humble, TX
I currently have an issue with scale deposits appearing on my plaster. The following are results from my latest visit to the pool store:

FC - 4.0
TC - 4.0
CC - 0.0
TA - 110
PH - 7.2
CH - 230
CYA - 60
TDS - 3200

I got this on Saturday. I have been adding 1qt of muratic acid daily trying to keep ph around 7.0 on my Taylor test kit. I am checking the ph twice a day and see to see a rise of about 0.4 from start to end of the day. I have tried using a pumice stone to knock off the spots but it seems to just tear up the stone. I currently have my SWG running at 50%. I am currently seeing roughly 40 spots on the bottom with the largest being roughly the diameter of a Bic pen. Please advise as to what steps that I might take to get rid of the scale as well as keep it in check. I am pretty certain that ph rise caused this mess (my bad).


Thanks-
Don
 
Hi, Don,

With your pH shooting up like that I'd have to assume it's a pretty new pool.

If that's the case, this may be pretty tricky but perhaps doable. CAREFULLY monitor your pH to see if you can keep it in a 6.8 - 7.0 range. With your pool water now just barely acidic, you may be able to continually brush those spots and eventually get the to return back to solution.

The second thought is that Waterbear has posted a kit from Allied Chemical that is supposed to address your issue without draining. I don't think anyone on the forum knows much about it however.

Lastly, is a drain and acid wash. That's effective but drastic and probably not a do-it-yourself thing.

Don, before you undertake any of these, check with your PB (if you're on good terms and he's pretty smart). The reason I say that is again assuming the pool is pretty new, I'm not sure of the affect any of these potential rememdies might have on new plaster.

My grammar stinks in this post but I hope you get my meaning.
 
Dave -

Thanks for the reply. My pool will be 2 yrs old in October. I have spoken to my pool builder and he mentioned that acid washing could rough up the surface a bit. He is supposed to come take a look at the surface but is currently trying to play catchup on new builds that got backed up when we had the 6 weeks of almost daily rain. In the meantime, I will take your advice and try to keep the ph in the range you suggested and keep the brush going.


Thanks-
Don
 
Well, your plaster should certainly be stable by now....I can't offer an explanation why your pH is climbing so rapidly. Perhaps someone else has a thought.

Meanwhile, lowering the pH will do no harm as long as you monitor it carefully. It wouldn't be a good idea to keep it below 6.8 but you get little effect if you go above 7.0 so it's a tough balancing act.

I would also pursue that non-draining kit from Allied Chemical. Waterbear will see this pretty soon and provide what info he can on it.

If lowering the pH works, it'll take more than a week to probably have any noticeable affect on the bumps.
 
TA is a little high for a SWG, if you bring it down, or let it come down by keeping the PH low for a while longer, the increase in PH will slow dramatically. I would aim for a TA of 70 or 80.

High TA and low PH and aeration will result in the PH increasing. The SWG supplies the aeration. The rate you quote doesn't surprise me. Bringing the TA down and letting PH go back up to 7.5, once the TA is where you want it, should take care of the PH increase issue.
 
I received the TF Testkit this afternoon and here are my readings:

C - 6.5
PH - 6.8
TA - 50
CH - 500 (I did this test 3 times and got the same results each time)
CYA - 80 (I added stabilizer after trip to pool store)
Salt - 3000

I have been adding muratic acid to lower ph but I suspect that I need to drain some pool water and refill to get than calcium down. I am not sure what was up at the pool store but their ch reading was off by a bunch. I am not sure exactly how they test but it looks like there are some discs and some droppers. Also, TA seems to be down a bunch but I tested it twice and I am not sure if it will come up with the PH.

Thanks-
Don
 
If you raise the PH with borax or washing soda/soda ash the TA will also come up, more so with washing soda than with borax. If you raise the PH with aeration the TA will not increase. Baking soda will raise the TA and raise the PH only a little bit.

As long as you keep your TA down around 70 or 80 you don't need to worry about the CH being around 500.

You should bring your PH up right away unless you are working on removing scale. I suggest using washing soda/soda ash/PH up, which will get you to about the right TA. Or you can use a combination of borax and baking soda.
 
Hi, Don,

Are you purposely keep the pH @ 6.8 (working on deposits) like we discussed or did you just temporarily lower it.

Your Alk will, to an extent, follow your pH up and down so, if you choose to run low pH, you can expect low Alk.....no harm as long as you monitor both with some regularity.

The high calcium is certainly indicative of the source for your scaling. Now that you've got pH under control, it should give you little problem, but I think draining and refilling to get it down around 300 eventually would be a good idea.

Your water is clear, isn't it?
 
Yes, I have been adding acid daily trying to keep ph at 6.8 hoping that I could perhaps brush off some of the spots. I am not sure how to explain the difference in the calcium readings from the pool store and mine. I have been taking my water there for several months and maybe they have been giving me a bad reading on it all along. It doesn't seem like a difficult test. Oh well, anyway I suppose that I will need to drain almost 1/3 of the pool to get the calcium to an acceptable level. My fill water does not seem to be anywhere near as hard as the pool. Should I wait to drain the pool and keep trying to get the spots up or go ahead and drain and get the ch fixed before getting back to deposits?


Thanks-
Don
 

Enjoying this content?

Support TFP with a donation.

Give Support
I wouldn't worry about the CH level. Check your saturation index when things get back to normal before worrying about the calcium level. Keeping CH between 200 and 400 is just a shorthand way of trying to get the saturation index right. If your TA is lower than the normal suggestion (120) then your CH can be higher.
 
Sounds like TexasBrew has my pool! Thanks for asking the question, Tex. Update if this takes care of your spots, I'll be following this advice and I'll update if it helps me also. My arms are going to be in top form after all of the brushing I'll be doing!
 
Don, I have no idea. I hate to sound discouraging, but I'm not at all convinced it WILL work. I think of it as more of a "try it and see, it's better that drain and acid wash" method.

My guess is it may take weeks.

Chemgeek may be able to help with how low you can take the pH. If you got stainless ladder(s), you may be able to pull them out and drop it even lower.....I just don't know.

I have no practical experience with this method so I am simply spouting off what makes sense to me. It is very logical to think that low pH will turn the calcium back to solution but I can't help with the "safe" parameters.
 
I have small brown and yellow spots that I think are scale (I have a thread for this in Algea section) and WaterBear suggested the a no drain acid treatment from United Chemical.

I spoke with a rep named Erwin from United Chemical and told him my situation and he said that I most likely have scale and what I should do is use 2 qts of their stain solution #2 along with 10 gls of Muriatic acid for my size pool (24,000gl). Procedures are to stop pump, dilute the 2 quarts of solution in 5gal buckets with pool water and start dumping along the perimeter of pool. Add 1 5gl muriatic acid and brush using combo brush (.5nylon .5 s/s) 15 min later dump another 5 gl of acid and brush thouroughly. Scrub twice a day then once a day for 4 days. Meantime use pucks in floater due to pump not running to prevent algea. After 4 days start bringing PH up slowly and then turn pump on and balance. I asked about the no drain acid wash and he said to do this procedure.

I haven't decided to do this due to having to close pool down for 4 days so I will probably do it at end of the season. I will call him to confirm the procedures.

My CH is at 260 and ph has risen to 8.0 a couple of times but I have been on top of it and have been adding about 1.5gls of acid a week since April (new pool). I think it got this way because my PB did not connect my equipment until 4 days after the plaster was put in. I did brush 3x's a day for the first week then 2x's a day for another week, but another poster has scale and his PB went a week before connecting his pump. This is what I am basing my opinion. I wonder if any one else had a new plaster pool go days with out filtering at start up.

I too will monitor this thread to see other's results.
 
10 gallons of Muriatic Acid (31.45% Hydrochloric Acid) in a 24,000 gallon pool is nuts. If I assume a starting pH of 7.5, TA of 100, and CYA of 30, then just 5 gallons will take your pH down to 4.0 and eliminate your TA (it actually goes negative so would measure as 0 and turn red immediately). 10 gallons would get your pH down to around 2.7 which is way, way too low. Perhaps locally for an acid wash this may be what is done, but I find it hard to believe that this is good for an entire pool especially if metal is present.

I don't know how low you can go and for how long. We know that going below 7.0 for an extended period of time is not good for metals, but I don't know the rates at various pH. Given some pools that have used Trichlor and gone down to around 4-5 in pH, I would say that for brief periods of time, so less than a week, that it probably doesn't ruin stainless steel. However, I can't say what it would do to pump seals, etc. but that's why they have you turn off the pump so presumably you would restore the pH before starting the pump again.

Sorry I can't be of more help. This is one of those things where experience will tell you more than theory.

Richard
 
WOW! United Chemical folks are into acid, alright!!!

I was doing the calcs on that when Richard posted. Folks, If normally very thoughful and diplomatic Chemgeek tells you something is "nuts", you need to pay attention.

10 gallons of muriatic in your pool may end up like the "China Syndrome" movie where the entire contents of your backyard end up resurfacing on the other side of the earth!! :lol: :lol:
 
My pb didn't hook up the equipment for 5 days after plaster. When they originally came to do it, they found out that the equipment wasn't wired into the electricity yet. This was a Thursday. On Friday the electrician they called said he'd be out Monday!!! I was FREAKING out!!! We were able to DIY it on Sunday w/ my electrician/brother's help. I think many of my scale stains are from that because they've been there since the beginning. When it bothers me I just get another Corona Light and, before you know it, I forget that I cared. ;-)
 
duraleigh said:
Folks, If normally very thoughful and diplomatic Chemgeek tells you something is "nuts", you need to pay attention.
Click to expand...
Just to put things into perspective, a pH of 2.7 is around the pH of many carbonated soft drinks and is a little higher than that of lemon juice. Stomach acid is below 2.0 and battery acid is somewhat less than 1.0. Muriatic Acid itself has a pH around -1.0 (yes, that's negative). The pH scale is logarithmic so though I said it was "nuts" to add 10 gallons to get to a pH of around 2.7, it's not going to instantly corrode metal nor burn through skin any more than dipping your hand into Coca-Cola or pouring lemon juice might -- but I wouldn't put it in your eyes or have an open cut so it is certainly not safe to swim in for that reason.

If there was no buffering of the water, then the pH would have been -1.0 - log10(10/24000) = 2.4 so the buffering doesn't do much when you add that much acid (i.e. the buffer gets mostly consumed with the first amounts of acid and then after that the water acts almost as if it's unbuffered).

As I said, experience trumps theory on this one and if going down to a pH of 2.7 is standard procedure and causes no side effects (with the pump off) when done for a limited period of time, then that's OK. If the idea is to dissolve the scale, then the process of doing that will have the pH rise (as well as CH and TA), though it won't rise to a pH of even 5.7 until 25 pounds of calcium carbonate scale and plaster has dissolved (the pH rises to 3.8 when 20 pounds dissolves). That just seems like a lot of weight to me so I suspect the timing of this is pretty important -- do it long enough to dissolve the scale, but not so long as to dissolve the plaster underneath the scale. And I'm not sure the scale dissolves that much more readily than the regular exposed plaster, but perhaps it does (due to irregular rough shape so more surface area per volume).

Richard
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply