Some questions for the chemists...

[RonPace]

Doing some surfing (pun) on pools, I notice that most (all?) articles are by Americans aimed towards Americans, where it seems the norm to march down a Walmart aisle and grab, pots of baking soda, borax, this acid and that acid, which is all double dutch to me, as we seem to only have pool shops selling a myriad of compounds under fancy names and no doubt, fancy prices as us Europeans are often gullible to paying high prices for snake oil!

So, here goes:
1. What is Muriatic acid and Dry acid? Are these available as everyday products in Europe? Which is best? Are these cheaper than 'Bayrol PH minus'?

2. What is Borax? Is it avaialable as an everyday product in Europe? Is it cheaper than "Bayrol Ph plus'?

3. Ditto for Soda Ash...

4. Ditto for Baking soda... I know this one should be straight forward, but try finding it France - the home of baking!! Is it cheaper than 'Bayrol AlcaPlus'?

5. Chlorine I am happy with - it is 'Javel' in France and stacked high in the 'Bricos' (DiY shops).

Now for my real question - Aerators! I am looking for something to aerate the pool with. I saw some tubes one replaces the return eyeball with on ebay, but typically, these are made for the US market and are not compatible with european threads. Searching for suitable products is not very successful so far. I guess we are just not pool aerators over here! Does anyone have any suggestions on an attractive way to aerate the pool?

Help appreciated!

[Teapot1]

Hi Ron,
Muratic acid is hydrochloric acid, €19 euros for a 20 litre bidon on a brico shed. 5 litre is also available should last a few years, I haven't added any for around 2 years. Its dangerous to skin, eyes, lungs so be aware.

Dry acid is ph- and sodium bisulphate in chemical terms. Adds sulphates to a pool so I dont use it.

Soda ash is sodium carbonate. pH+

Baking soda is bicarbonate of soda, supermarkets or if you need a fair bit ask your baker! They will often sell you some but why would you need it? American site tell Americans how to run their pools based on chemistry for gunite plaster pebbletec pools and not for vinyl liner and fibreglass pools which can run on much lower levels of ALK around 45ppm and have rock solid pH levels.

Depends a bit on the return fittings and if you are a bit practical? Post a bit more later with aeration but pointing the returns skyward is a start.

[RonPace]

Thanks so far Teapot! Tell me more about Hydrochloric acid please - I can use this instead of Ph moins, yes? Will it harm dosing pumps - in particular the solenoid type that I have, or will it harm any of the plastic/nylon delivery tube fittings? I use little of Ph-, in fact the big bidons I have to buy usually go off (they get sticky and the liquid goes black) long before they are consumed, so straight HCl acid might be better and certainly cheaper...ok, there are safety issues.

For raising Ph, when does one use Borax or Soda Ash? I read somewhere the other night that the best way to raise Ph is aeration. This got me thinking about aeration as it might be good for the TA, but an aerator will give the soothing sound of flowing water and - as my pump decided to click off for what must have been a few days - can be a warning for pump not working or even filter getting gummed up. Hence my interest. But, is it possible to over aerate and send the Ph sky high?

[Teapot1]

Hi Ron
Yes you can use hydrochloric very effectively for pH reduction. As to the materials used in your dosing pumps you would have to look it up. Most use materials that can easily cope but it can accelerate the aging of some parts. My peristaltic pumps pinch tubes are replaced about 2 yearly and the pvc delivery pipe each year for safety as I am not on site to care for the equipment. That said, if you do get the Alk down to around 45ppm like me and some of my customers you wont need ph- for months. In actuality I disconnected my pH pump years ago and any adjustments are made manually and that hasn't happened in 2+ years so I just keep a single litre of hydrochloric and thats around 4 years old now. Happy days eh. If a probe malfunctions or some other component you can get a serious over feed of pH- from any source and damage the liner or the people this is a risk factor I have eliminated and from 1 client who fed 20ltr of hydrochloric acid into his pool in one go after just such a malfunction of his doser and another who emptied a large quantity of acid into his plant room following a pinch tube failure, when you get the Alk lowered you can simply do without the pH doser.

Now it is important to say when the Alk is lower at around 45ppm the pH can move a lot easier so any adjustments will require a lot less of plus or minus chemicals than before. The acidic nature of galets for instance will cause a drop in pH over time, the odd one or two are fine.

Borax, it also acts as a pH buffer but at a lower level than bicarbonate of soda which likes pH of 8.1-8.3 when disolved in water, a bit too high for most pool users. Borax, sodium tetraborate is used by some as a low dose algaecide in the background, it also makes a pH buffer solution around the lower 8 and high 7's in a pool situation (non pool it buffers at a higher level 8.5- 9 pH.
Do you really need it? Not unless you have a concrete, plaster, pebbletec or tiled pool and even then its questionable, get the alkalinity lower, the pH will be a lot more stable and you can forget these add ons, i am more for the pure water principle (only whats really needed) than additives.
CYA is also a buffer to pH in a pool at the correct level it buffers in opposition to the alkalinity chemicals helping to stabilise things. Too much CYA and the pH can move downwards as I have seen many times in pools with 200+ ppm of CYA so you can see what really balancing water is all about rather than the pool shops view and why we ask for full water test results on here.

Can you over aerate, no not usually, the dilution of the chemicals in the pool water and the level of alkalinity means the highest it will usually go pH wise is 8.1-8.3 dangerous if you have iron or copper in the water as they drop out of solution and stain things. But nothing to worry about in the short term. Also running the pH a little higher 7.8 compensates if the water looks a little aggresive on the calcium saturation index (langlier index) as pH has a much bigger effect being logarithmic than a few ppm's of bicarb or CYA. It has been proven that the water at higher pH is comfortable to swim in and the eyes are very happy at that level, red eyes are more common at lower pH 7's.
Aeration is the better method of pH control when you reduce the alkalinity from the industry levels to what we know works best but that of course would damage pool shop sales!
I did carefully carried out tests many years ago with airstone water towers and at an alkalinity of 120ppm the pH would rise to 8.1 in an hour. Lower alkalinity at around 45ppm resulted in a stable pH after 24 hours of continuous aeration.

[Denniswiseman]

I use a very large pond aerator for aeration with 4 large airstones

[RonPace]

Interesting this aeration!

I have angled the return eyeballs skyward so that only about half the aperture is working and get exactly the sound I am looking for, so I shall not be looking at the attachments any more! I might consider a stainless 'fountain' mounted on the terrace and plumbed into the reurn line. Maybe a winter project.

After a few days, I see the Ph level up to 7.9 (I have disconnected the Ph minus doser) from its usual 7.4 to 7.6 range, so something is happening! If I keep the eyeballs set as they are, can I assume this level of 7.9 will now be the norm, or will it continue to rise as more and more water is exposed to the atmosphere?

If you say that pool water is ok with a Ph of 8 - should I consider altering the setting of the doser to come in higher now?

Interestingly, I see after the few days of new eyeball settings, my TA has gone down from 149 last week to 109 today. Is this a result of aeration too?

My CYA has also gone done to 61 from 72 last week (I am now only using calcium tablets and bleach - the Zodiac SWG is turned off)

You have mentioned a few times of having an ideal TA at 45. How is this actually achieved?

[Teapot1]

Ok Ron, with the pH at 7.9 you would add acid to reduce the pH down to 6.8- 7 and then aerate until the pH rises to 7.9+ at which point the alkalinity will be lower again. Repeating this process until the alkalinity is lower around 45-50ppm and pH is normal. Because pH is a logarithmic scale the pH will change less as you go on. It will as I said earlier take less acid each time you do this as the alkalinity lowers so be careful you dont dip too low on pH.

[RonPace]

What you are saying is that one can hold a pool together with a cannister of bleach, hydrochloric acid and a really good aerator - ok, simple terms, but it seems what you are saying, yes?

Why do, I ask, have loads of little tubs of this and that I ask? Yes I know, the pool store makes lots of money from me!

Now that you have shown me how to separate the reliance of TA on Ph levels, and not be afraid to take PH higher than 7.5, what do you recommend to be the ideal pool condition of TA, Ph and CYA?

I am a bit nervous when it comes to chlorine and always tend to keep levels high - up around 3. Is this upsatting anything such as TA or PH. Indeed, can high chlorine even kill CYA despite it being needed?

[RonPace]

Hi Dennis - will you expand further on your aeration please - what it is exactly and how it is installed?

Reading more on aeration, I see it is not only a matter of passing water through air, rather it is passing air through water. If I am going to embrace this idea, then I want to do it properly, but trawling through the web, I do not see anything specifically for swimming pools. Yes, I see pond aerators and understand them, but it does mean another pump and tubes across the terrace into the water with stones on the end. My issue here is that I can see these getting abused - it is bad enough leaving my robot in the pool, it seems to be regarded as a toy...a bubbling stone is going to get them really excited!

I was wondering if anyone has come up with a inline aerator that could be put in the return line after it leaves the filter...?

[Denniswiseman]

It's as you describe but it's not left in permanently. The best thing is that the air travels from the bottom in the deep end through a lot of water
You could probably make one that fits into your returns with a venturi in a tee but that would be near the surface so not as efficient
Chlorine isn't high at 3 in fact you should base your level on your CYA
Chlorine / CYA Chart and Recommended Pool Levels
You can safely swim with a pool chlorinated upto your slam level for your CYA

[Teapot1]

Hi Ron, this is what I did to make an aeration device.
https://youtu.be/3Cj4-6nhNH4

[RonPace]

Thanks Dennis. One day I will get a handle on all this correlation between the various levels, as I had not appreciated or forgotten the CYA and chlorine relationship...
I take your point in having aeration at the deep end.

That is pretty impressive teapot! I like it, As it happens, I have a couple of submersible pumps not doing much - I might experiment. I will let you know.