Recommendations on Liquidator vs. Peristaltic Pump vs. SWG?

[Chuck_Davis]

I'm working on pulling together several data threads into what I hope will be a strategy (and not a tangled mess). I would appreciate any comments or suggestions.

1) Added borates per TFP recommendation in the spring. Very pleased with the results.
2) Using Rainbow chlorinator and chlorine sticks. CYA went up from 30 to 108 over the summer.
3) After 3 years I've still been unable to find the source of copper and iron that is causing stains. Getting ready to do an AA treatment. I'm also going to start using Jack's Magic Blue Stuff as a sequestrant instead of Natural Chemistry Scale Free (which was recommended by Natural Chemistry as being a stronger sequestrant than Metal Free).
4) The pool has a waterfall-style water feature that causes some aeration.
5) The pool surface is epoxy paint. The epoxy paint manufacturer (Zeron) recommends a TA range of 125-150 ppm and a CH range of 175-225 ppm. I add 1/3 of the CYA reading to the TA numbers to account for the contribution of CYA to the TA reading. (E.g. with a CYA of 60, I try for TA in the range of 145-170.)

Due to the CYA rise I'm thinking of switching to a liquid chlorinator or SWG. Folks on TFP seem happy with the Liquidator. My concerns about high chlorine levels damaging the pump seal, spider gasket or heat pump core seem to have been addressed on TFP. SWG's and peristaltic pumps are a lot more expensive than the Liquidator. Speaking to the owner of a pool maintenance company (for vacation coverage), he said that his clients with SWG's have lots of problems with water quality and failing controllers.

The TFP recommendation for pH with SWG's is 7.5-7.6. The TFP recommendation to minimize staining is a pH of 7.2. I wonder if an SWG would work at cross-purposes to my stain-fighting efforts.

This may become a theological discussion, but I would appreciate folk's thoughts and recommendations on Liquidator vs. peristaltic pumps vs. SWG chlorinating systems. I would especially appreciate information from anybody who has used several different types of systems.

I'm planning to do the AA treatment and then dump some water (with its metal) to drop the CYA. I'll then refill and add sequestrant. Does this make sense or is there a reason to drop the CYA before the AA treatment?

Thanks!

 

[chem geek]

Re: Liquidator vs. Peristaltic Pump vs. SWG

You probably will not be able to satisfy the TA requirement from Zeron of 120-150 ppm and hope to have any pH stability at a lower pH. That high a TA combined with aeration will most likely have the pH rise and want to be up near 8.0 or so. I don't understand at all their requirement for such a high TA. They just be assuming that Trichlor pucks/tabs are used and that the pH would normally be low and they don't want that for their epoxy paint, but that's just a guess. I think you will be far better off with a TA of 80 ppm.

As for minimizing staining, you'll probably need to use a metal sequestrant as I don't think it will be easy for you to maintain a pH of 7.2 without using a lot of acid or having the TA be even lower.

 

[Chuck_Davis]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

Thanks, Chem Geek.

The TA recommendation from Zeron is actually lower than other epoxy manufacturers, who recommend >150 ppm or 160-180 ppm to minimize chalking. (One manufacturer also recommends a pH range of 7.6-7.8!)

I'm thinking it may be because of the borates, but I've not had any problem holding the Zeron specs this summer. There's been a little bit of upward drift in pH, but nothing over 7.6.

Do you have any thoughts or recommendations on Liquidator vs. peristaltic pumps vs. SWG? Reading up a bit more on SWG's, it looks like the high TA might result in increased cell maintenance. The Liquidator certainly seems to satisfy the K.I.S.S. principle, and borates apparently reduce the issues with precipitated solids.

 

[chem geek]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

So by "chalking" are they referring to calcium carbonate? If they want to saturate the water with calcium carbonate, then that can be done with a higher CH level, not just having a higher TA. It's the saturation index they should be concerned about, not TA by itself. OR is chalking just caused by lower pH? If that is the case, they should just say that and have the pH maintained higher. One doesn't have to have the TA that high to do that.

As for options for automation, there are pros and cons with each system. If you don't mind buying and hauling chlorinating liquid or bleach, then The Liquidator or peristaltic pump are decent options. The SWG is primarily for the convenience of not buying and hauling chlorine.. Since The Liquidator is relatively inexpensive, you could try that first.

 

[Chuck_Davis]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

Especially since there are search terms in this thread that might get hits by other folks with epoxy pools, here are some <snips> from various web sites:

Epoxy Mfr 1:

Chalking is a natural weathering process of any Epoxy coating, Chalking is apparent as a fine powdery deposit on the paint surface, intensity of chalking is dependent upon pool water chemistry stability, water type, light intensity and overall stability of the water conditions to which the Epoxy coating is subjected. Chalking is accelerated by a deposition of soluble salts from the water onto the coating surface and by unstable pool water chemistry, high chlorine levels also affect chalking. Regular brushing, followed by at least 8 hours filtration, will minimize chalking levels and maintain the coating in good condition.

Epoxy Mfr 2:

• The shock of calcium hypochlorite can cause a white, bleached look to the paint film, leaving a whitish deposit.
• A chalky substance can be created by over treating the water with shock, bromine, ozone and ionization. It is not the paint breaking down. We suggest a natural polymer product or clarifier that can reduce the chalking problem.
• Iron in the water from rust in the filter system may leave deposits and stain the film.
• All epoxies will chalk to some degree due to exposure to UV rays of the sun.
• Follow manufacturer’s recommendations for proper water chemistry.

Epoxy Mfr 3:

7. IMPORTANT. Total alkalinity (TA) should be adjusted close to 180ppm, and maintained within the range 160-180 ppm. White powdery deposits on the coating surface generally indicate low Total Alkalinity. Refer to our ‘Useful Hints’ following further down the page. If these deposits are allowed to develop unchecked, this may result in reduced life expectancy of the coating due to the abrasive action of pool cleaners on the paint surface.
NOTE: CHALKING is a natural process during the life of the XXXXX Epoxy Coating. By minimising chalking, the coating life will be maximised. To minimise chalking, Total Alkalinity should be checked regularly and maintained in the range 160-180 ppm ALL OF THE YEAR.
8. pH should be maintained in the range 7.6 > 7.8.
9. Test the water regularly for Calcium Hardness, the reading should be maintained in the narrowest possible range 280-320 ppm.

Pool Supply Company:

Some painted surfaces will begin to break down over time. The results can be dull, hazy water, as well as a white powdery residue that can rub off on hands, feet and bathing suits. To avoid this, water chemistry and maintenance are the key. The total alkalinity must be in the correct range. At least 150 PPM to 200 PPM. 175 PPM is ideal. If the alkalinity is too low the pool paint will rub off. Harsh shock treatments will also cause the pool paint to chalk. Use lithium or a di-chloro base shock for maintenance. Harsh shock treatments like calcium hypochlorite will contribute to the deterioration of the pool paint job.

Pool Repair Company:

Chalking results over time and causes a white powdery residue that can rub off. To avoid this, water chemistry is the key.
The total alkalinity 150 PPM to 200 PPM. When alkalinity is too low the paint will rub off. Shock treatments can also cause the pool paint to chalk.
Super-chlorinated water can cause "bleached-out" look.
The "shock" of calcium hypochlorite can cause a whitish deposit.
Epoxies will chalk to some degree due U.V. rays from the sun.

 

[Chuck_Davis]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

Note - I recently started using a "whale tail" brush, which has more and stiffer bristles than a standard brush. The "whale tail" results in much higher pressure on the surface (wall or bottom) being brushed. The first brushing knocked loose a lot of chalk. Subsequent to that first brushing the pool surface feels much less slippery and brushings don't yield much in the way of chalk.

 

[chem geek]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

Yeah, some of these guys even go into more "technical" detail that doesn't make sense such as this link that says:

A misconception regarding pool coatings often involves advanced and excessive "chalking" or "cloudy" water. This most often refers to pools coated with epoxy, but can occur on pools coated with rubber-base coating.

Kelley Technical Coatings has worked to find a cause and solution of this water condition, knowing full well that the coating is not a fault.

The recommended water chemistry of a coated pool is different from that of a non-smooth surfaced pool. For instance, if the total alkalinity drops too low, minerals in the water can "fall out" of solution, most commonly calcium carbonate. This white precipitate is scale, and will feel greasy or oily, thus givng the physical impression of paint. Should you encounter a pool coated with epoxy that is chalking badly, adjust the water chemistry according to the following:

Adjust the total alkalinity to 125-150 ppm.
Add a sequestering or chelating agent, following label directions.
Add a clarifier or flocculent to the water. This will bind these free particles together so they may be trapped by the filter. A filter cartridge in the 5 micron range is recommended. A 30 micron cartrridge may not trap these particles.
Turn on the filtering system so that it will operate 16-20 hours per day for five days.
Brush the sides of the pool for five days.
Keep the calcium level at 175-225 ppm.
Typically this should clear the pool water. At that point, the water chemistry should be kept adjusted accordingly.

On a newly coated pool, in addition to the recommended water chemistry, we also recommend the use of a sequestring or chelating agent (stain and scale control) especially during the swimming season. Plus, periodic brushing of the walls, about once a week.

Calcium carbonate will "fall out" of solution, that is turn into scale, when the combination of pH, TA and CH are high, NOT when the total alkalinity drops too low as they claim. Their CH and TA would have a near-zero saturation index at a pH of 7.5, but that would be hard to maintain and more likely the pH would tend to get high towards 8.0. Very strange advice from all these guys.

This link indicates that epoxy paints may contain calcium carbonate as a filler so that would make sense to have the saturation index near 0 and perhaps they just say to have the TA high which makes the pH high to ensure that and then the CH level doesn't have to be as high. It still doesn't make much sense as to why one couldn't instead have the CH higher and pH and TA lower unless there is some additional requirement for the pH to remain higher.

 

[Chuck_Davis]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

Veerrrryyy Interesting................

I spoke with Kelley Technical Coatings, the manufacturer of Zeron epoxy pool paint. It turns out that the recommendation for a TA level well above the normal range and the recommendation for a CH level at or below the bottom of the normal range came out of a meeting 20 or so years ago between the chemists from three epoxy paint manufacturers. These recommendations have since become "conventional wisdom." A lot of the manufacturer and vendor recommendations and reasonings cited above appear to be misstatements of this conventional wisdom.

The Zeron rep did say that he doesn't get any callbacks from folks that follow their recommendations, indicating to him that their recommendations do work with their epoxy coatings. It is my impression that I've had less "chalking" after following their recommendations since last spring.

The foundation for their recommendations appears to be that what people perceive as "chalking" on epoxy pools is, in fact, "fallout" of calcium carbonate "residue" from the water. This white chalking is more visible on a smooth, sometimes colored, epoxy surface than it is on plaster.

The Zeron rep said that Epoxy pool coatings do "chalk" slowly over the years as a result of UV light, but this true chalking will be the same color as the paint. E.g. a blue painted pool would have blue chalking. White chalking on a blue painted pool (which is what I had) is (probably) some form of calcium that has precipitated out of the water.

To recap, Zeron's recommendation for water chemistry is a TA range of 125-150 (well above the typical recommendation) and a CH range of 175-225 (at and below the bottom end of the typical recommendation). They also recommend against using calcium hypochlorite for sanitizing. I don't know if there is a direct precipitation onto the epoxy from the cal-hypo or the issue is "CH creep" as documented elsewhere on TFP.

(Reminder - Subtract 1/3 of your CYA reading from the "raw" TA reading to get a true TA reading. You can also shift the target TA range up by 1/3 of the CYA reading.)

Chem Geek believes that these water chemistry values will cause pH to be unstable, but that was not my experience, possibly because I am using borates.

Coming back around to where this thread started, the simplicity of using liquid chlorine for sanitizing, the issues of CYA buildup (from stabilized sanitizers) and/or CH buildup (from cal-hypo), the cost of a peristaltic pump or SWG and the maintenance and repair costs of an SWG have led me to go with the Liquidator. I'm hoping it will be delivered today.

 

[linen]

Re: Recommendations on Liquidator vs. Peristaltic Pump vs. S

(Reminder - Subtract 1/3 of your CYA reading from the "raw" TA reading to get a true TA reading. You can also shift the target TA range up by 1/3 of the CYA reading.)

I see nowhere in the Kelly technical bulletin referred to above, where they call out ATA (Adjusted Total Alkalinity). That would make the TA (Total Alkalinity) even higher if they did.

With that said, having to maintain a TA that high seems [s:22ip6npl]crazy[/s:22ip6npl] counter-intuitive when trying to minimize chalking (calcium carbonate)...especially where one has high fill CH (such as mine which is easily over 300 ppm typically).

This link indicates that epoxy paints may contain calcium carbonate as a filler so that would make sense to have the saturation index near 0 and perhaps they just say to have the TA high which makes the pH high to ensure that and then the CH level doesn't have to be as high. It still doesn't make much sense as to why one couldn't instead have the CH higher and pH and TA lower unless there is some additional requirement for the pH to remain higher.

This idea helps make it a little more understandable to me, is it possible that 20+ years ago when they were figuring out their recommendations, maybe the lsi/csi was not understood as well as today? However, with TA as high as recommend, it seems like you would always be fighting ph rise.

Let us know how the liquidator works out for you.