TA, PH and aeration

austinnichols101

LifeTime Supporter
Feb 9, 2008
38
Miami, FL
#1
I'm using the acid / aeration technique to drop the TA levels. The acid part was easy and I dropped the pH down to 7.0 - 7.2. TA was at 180 when I started the process.

Now I'm aerating the pool by injecting air into the skimmer. I'm able to roughly control the amount of air back at the pump by using the intake valves for the skimmer and the floor intake. I can see air being mixed in at in the pump and I can clearly see streams of bubbles coming from the returns and I'm getting quite a bit of surface breakup. However, I'm not seeing any measurable change in the pH after running overnight. I've been running this setup for approximately 12 hours.

The pool is an 18,000 rectangular diamond bright. Are there any guidelines on how long / how much aeration it takes to achieve results?
 

JasonLion

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May 7, 2007
37,879
Silver Spring, MD
#2
If the aeration was being effective you should have seen some measurable change overnight and reach your target within a few days at most. Really high levels of aeration can show dramatic results in a couple of hours. There is no easy way to measure how effective any given aeration method is other than trying it and seeing what happens. In general, aeration is most effective when many small bubbles are produced, rather than fewer large ones. Perhaps you could try pointing a return up so it breaks the surface and see how that does.
 

austinnichols101

LifeTime Supporter
Feb 9, 2008
38
Miami, FL
#3
Thanks - that gives me a good idea of what to look for.

My pool setup is unusual in that it has a a dozen or so return jets that are located in the floor of the pool and then three return jets that are fixed and designed to move debris along the surface to the skimmer. I've thought about changing out the surface jets but they don't appear to have screw fittings.

I'm going to investigate a venturi as it might allow me to obtain better control over the amount of air / bubble size. I've also got an old 1400 gph mag-drive aquarium pump that I could press into service to break up the surface.

Upside is that overall the pool is REALLY starting to look nice. Here's a picture from this morning. Only 6 days of BBB and the pool is looking the best I've ever seen it. You can just make out the floor jets in the picture...

 

austinnichols101

LifeTime Supporter
Feb 9, 2008
38
Miami, FL
#4
Success! I put the mag-drive pump in at the stairs and positioned it so that the output stream was just at the waterline which produced the maximum number of small-sized bubbles. I let it run overnight and I've been able to see a move in the pH from around 7.0 to 7.2.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#5
I'm glad it's starting to work out for you. The maximum aeration occurs when the bubbles are small (higher surface area to volume ratio) and their contact time in the water is long. So the fastest pH rise we've ever seen was when an air compressor was used with a nozzle that had many small holes producing tiny bubbles and where this was put into the deep end of the pool.

In my own pool, I find that pointing the return jets upward with a high flow rate does a little aeration, but not particularly fast. What worked a little better for me was to take my pool cover pump and pump pool water into a shower I had. Unfortunately, the pool pump wasn't strong enough to pump through the shower unless I removed the shower head, but it turned out that having a flow of water about 6 feet high aimed at the pool caused enough aeration to be noticeable.

Somebody made a jet device you connect to your return and it just pushes a stream of water into the pool and they found that effective (I can't seem to find the posts that show it). I'll bet that if this was connected to each return, that this would be a good deal of aeration.

Richard
 

austinnichols101

LifeTime Supporter
Feb 9, 2008
38
Miami, FL
#6
Liquidator = Aerator?

I installed my Liquidator this morning and later this afternoon I stumbled upon an interesting 'feature'. If I loosen the small black cap on top of the flow meter it causes the suction side of the pump to suck in a ton of small air bubbles and thus gives me a great way to aerate the pool (and raise the pH). Combined with a properly adjusted return inlet, I now have major aeration capabilities with minimal effort.

The only downside I can think of is that I'm ainjecting air into the suction side of the pump and that I'm not flowing clorine while I have the liquidator configured this way. Should I be concerned at all about cavitation with the pump?
 

JasonLion

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May 7, 2007
37,879
Silver Spring, MD
#7
Small amounts of air getting to the pump is not a problem. If too much air gets in you might lose prime. Cavitation is something else entirely, a vacuum forming behind the pump vanes.
 

Hotrod30

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LifeTime Supporter
Dec 22, 2007
504
Central New York
#8
They make a little device that attaches to the return fitting that injects air into the return stream. I have one sitting in the pool shed; but for the life of me I can't remember the name of it. It screws on the return instead of the eye. It has a small yellow plastic tube that comes above the water level and it puts alot of air into the return stream. I know I mail ordered it; but I can't find a picture to post. It was only about $19.95. I'm really getting old and forgetful.
 

duraleigh

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In The Industry
Apr 1, 2007
31,271
Sebring, Florida
#9
I think I might like Hotrod's device a little better than bringing air in on the suction side. If your pump is like mine, any air at all really causes it to rattle.

I'm sure there's little harm doing that from time to time but it gives me sort of an uneasy feeling listening to my pump make that noise.
 

induce

LifeTime Supporter
Apr 14, 2007
92
Murfreesboro, TN
#11
Hotrod, i like that device. cheap too.
i bought a polaris fountain on ebay to get my aeration. pretty simple to use, kinda cheap looking. but shoots the water up a couple of feet.
i had to fill with well water and the ta was above 300! the fountain and acid got it down in about 3 days. put it back in the box for future use.
 

Rangeball

Well-known member
May 25, 2007
785
#12
I've been imagining building something like what hotrod linked to for awhile now-

http://www.poolsupplies.com/cgi-bin/Com ... add=action

I assume it works on the venturi principal. Anyone have a clue if a piece of pvc screwed into the return with a T in the middle and a much smaller diameter piece of pvc in the top of the T pointing up out of the water to provide suction wouldn't work?

Or, any idea what the inside of the linked aerator might look like?