Need help with algue in a oxygen pool

[chem geek]

For example -- and Chem_Geek may correct me -- there are STILL no pool books that acknowledge that the only EFFECTIVE way to lower carbonate alkalinity levels is via reduced pH *PLUS* aeration. And that is one of the bits of the BBB Method that's ironclad, with scads of anecdotal evidence, a comprehensive analytical explanation (thanks to Chem_Geek), and some clear experimental evidence. But, folks prefer being wrong, to admitting that they have been wrong.

As I noted in the post Certified Pool Operator (CPO) training -- What is not taught, the 2009 "CPO® Handbook, National Swimming Pool Foundation®" with front cover title "Pool & Spa Operator™ Handbook" indicates that at higher levels of TA, the pH is usually higher than ideal and becomes very difficult to change, but does not indicate that TA itself is a source of rising pH due to carbon dioxide outgassing. In the Spa & Therapy Operations section, when discussing pH, there is a discussion of aeration and carbon dioxide outgassing causing the pH to rise (and it says the TA decreases which is incorrect; the TA only drops when acid is added as acid lowers both pH and TA). However, even in this discussion it is not made clear that this effect can be reduced by lowering the TA level (nor how to do that efficiently) and supplementing pH buffering with a different non-carbonate pH buffer such as borates.

So there are bits and pieces of the correct chemistry, but not the definitive procedure as Ben describes in Lowering Swimming Pool Alkalinity -- A Step By Step Guide. Unfortunately, the industry still too often touts the "slug" or "acid column" method which is dangerous and inefficient as described in this paper, a shorter version of which may be found in this paper and this link. The fact is that 25-1/2 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons will lower the Total Alkalnity (TA) by 10 ppm no matter how you add it. The only thing you can affect is how quickly you can bring the pH back up without changing the TA, and that is accelerated by increasing the amount of aeration and having the pH be lower (at least near the water surface). This chart shows how over-carbonated the water is with respect to being in equilibrium with the air. The rate of outgassing increases with how far you are out-of-equilibrium, though the effect with TA is non-linear and appears to vary as the square of the TA (this effect is not shown in the table).

[PMS SAyMI]

Ok Chem geek first its quicker - firstly let me tell you i was terrible at science in school and not much better as a adult have read your reply 3 times and whilst i just about get it my head is now mash, I think Bens paper is a little easier to digest however really do appreciate your input keep your thoughts coming but the simplier put the better for me lol.

Ben - one of the reasons my business here is so successful is because i am honest in what i am knowledgeable about.

But, what I can tell you is that, if you are in pool chemical sales in the USA, there are 3 possible attributes you can have:
1. you can be knowledgeable
2. you can be honest
3. you can be an aggressive salesman of profitable chemicals

my thoughts at the moment are to continue to sell the products in the retail outlet as mostly they do what they state, I already wont sell a product in the shop if i have tried it and it does not do what it says on the box.

if i try your method and it all works as it should which i suspect it will i think what i will do is use it on the pool maintenance side but only divulge it in the retail outlet if a customer for example asks me if i have heard of the method or if i have heard of using household products in swimming pools - at the moment i can honestly say it is a theory im playing with but have no visible proof, if it all works then yes i would happily tell customers that we are successfully using it in our pools, again i would not offer the information but i would stand by it if asked directly.

But, I made a serious mistake that ended up costing me most of my business. I'll warn you, so you don't do the same.

With commercial pools, staff tends to change from year to year, and after three years, typically none of the people who hired me -- and who remembered how badly the pool had run before -- were still at the pool. They'd heard about it, though. But, after six years, the staff simply assumed that the way their pool ran was the way pools mostly ran, and thus, that I was doing nothing special.

I really appreciate your warning but we dont work like this - you see we dont train staff, we have our own (my staff trained to my standards) so clients both private and commercial pay us and our staff go in and maintain the pool - so there is no fear of a changeover of staff just a changeover of management committees that do occasionally think they can get better for cheaper but some you lose and some you dont, also we always have photos of pools that were very bad on the start as we regularly use before and after photos in the retail outlet. as our contracts are yearly and with commercial pools we are invited back the following year to re-tender we normally include these photos.

now going back to your bbb method the only thing i dont understand is what do you use for algae apart from chlorine shock if anything - also i would like to give you 2 typical pool problems that we have come across more than once and see what your thoughts are.

first problem is although the most of our pools are the typical concrete pools the other common pool here is fibreglass - for some reason unknown to me all fibreglass pools have low ph normal between 6.7 - 6.9, all other chemical values are good but they all have this one thing in common and does not matter how much ph plus you put in they come up for a week and then go back down. - we now just leave them down but your thoughts on this interest me.

second thing is we have a small portion of pools with a orangey brown staining in the grouting again all chemical levels are fine now my thought is with this it normally starts on the floor and left alone it will rise up the walls you can brush it all off with a normal nylon brush or metal brush but the following week it is back and looking no different, we have tried shocking, tried a anti algae for mustard algae but nothing works. we have even emptied one pool and acid cleaned it but within 18 months it was back - all our pools are brushed weekly and levels are kept within good ranges.

sorry Ben I know im loading you with different things and problems but this is the most useful place i have found and eager to do whatever it takes to ensure my company is not only the best but most knowledgeable in the area and lastly willing to try everything to help us get there.

[waterbear]

first problem is although the most of our pools are the typical concrete pools the other common pool here is fibreglass - for some reason unknown to me all fibreglass pools have low ph normal between 6.7 - 6.9, all other chemical values are good but they all have this one thing in common and does not matter how much ph plus you put in they come up for a week and then go back down. - we now just leave them down but your thoughts on this interest me.
Fiberglass pools are common here also. In fact I have one myself and the only reason I know of that the pH would be low is because of the addition of an acidic chemical such as trichlor or dichlor or MPS. Is the TA as high in the fiberglass pools as in the plaster ones? Is acid being added for any reasons? Posting a full set of test results can tell us a lot more about what is going on.

second thing is we have a small portion of pools with a orangey brown staining in the grouting again all chemical levels are fine now my thought is with this it normally starts on the floor and left alone it will rise up the walls you can brush it all off with a normal nylon brush or metal brush but the following week it is back and looking no different, we have tried shocking, tried a anti algae for mustard algae but nothing works. we have even emptied one pool and acid cleaned it but within 18 months it was back - all our pools are brushed weekly and levels are kept within good ranges.
Once again without having water test results it is hard to say what is going on in these pools but I do have an idea. What is the chlorine source you are using? Is it a stabilized chlorine such as trichlor?

Each pool is different, as you well know, and if you can post some of the acutal numbers and puoducts used (chemical names) from your 'problem pools' we might be able to figure out what is going on in them.