How can I aerate?

[phalcon51]

My TA is a bit high and the Pool Calculator is telling me to add MA to lower the pH to 7.0 - 7.2 and then aerate to bring up the pH. I don't have any water features to aerate with, but I do have a small 1/4 hp, 23 gpm submersible pump from Harbor Freight. If I put the pump on a step just under the surface (to minimize pumping losses) and put a fan spray head on the end of the hose with it angled up into the air and falling into the pool, would that be a very effective aerator?

Actually, I just put the pump on the first step and turned it on with no hose connected and it shoots a column of water about 3-4 feet in the air before splashing back down into the pool. Would this be good enough? I'm trying to get the TA from about 110 down to 80-90. Any rough idea how long I might have to leave it running - hours? days?

 

[Isaac-1]

I would at least try to angle it out over the water so you have less splash out.

Ike

 

[Johnny B]

My guess would be closer to days than to hours.

 

[chem geek]

Instead of sending the flow up, see if you can point it into the water at an angle to create a churning effect that also creates waves in the water -- especially if you can put a jet nozzle (or even better, an aerating nozzle) on the end. That then involves more of the pool surface and can also add more air bubbles into the pool water (see some of the pictures in this post where they point the jets downward -- there's another post somewhere I can't find that shows really strong jets that are quite effective). You can also point your returns up with the pool pump on high to break the surface of the water again creating wave action.

The best is an air compressor producing lots of tiny bubbles starting at the bottom of the deep end of the pool, but that's not always readily available.

 

[Richard320]

Check out this recent threadfor an idea. One of the replies has a link to an even earlier thread on the same topic.

My experience has been that there's an inverse proportion to how long it takes, depending on how high you start. Meaning: to drop from 150 to 120 is quick. 120 to 90 takes longer. And so on. What you're looking for is a seriously disturbed, churning surface. In my case, it's easy. Full flow to the spa and the spa booster on. The surface appears to be boiling, all sorts of splash wetting the deck for about a foot all around.

 

[phalcon51]

FWIW.....

I started with a TA of about 110 and added enough MA to bring the pH down to 7.0. At the same time (Sunday evening) I set up my small 1/4 hp Harbor Freight sump pump on the first step in the shallow end half on and half off a 1" thick paving stone so it would angle out over the water and reduce the splashing on the deck. I also angled up one of the return eyeballs so that the water just broke the surface. I monitored the pH and TA twice a day, in the morning and the late afternoon. By Monday morning the pH was 7.0 and the TA was 70. Tuesday morning the pH was at 7.4 and the TA was nudging 80. By Tuesday evening the pH had risen to 7.6 and the TA to a solid 80. By this morning (Wednesday) the pH was up to 7.9 and the TA remained stable at 80. When I came home from work this afternoon I checked it again the the pH was up to 8.0 and the TA was still at 80. I added enough MA to bring the pH down to 7.4-7.5. So all in all it took about 60 hours of aeration to raise the pH back up from 7.0 to 8.0. I probably could have knocked 12 hours off of that by stopping the aeration when the pH reached 7.8.

I hope this is useful information for anyone else needing to do the same thing.

Gary

 

[chem geek]

The rate of outgassing is faster at lower pH, so adding more acid when the pH gets to 7.2 or so makes the process go faster, though obviously requires more effort with more frequent acid addition. This chart can give you a rough idea of the relative amounts of carbon dioxide in the water compared to the normal amount from air (which would be a "0.0" in the table) where you can see that a lower pH increases the carbon dioxide amount greatly. That helps drive off this carbon dioxide with aeration more quickly.

 

[phalcon51]

Is it necessary or advisable to keep the pH at a low level (7.0-7.2) while aerating for a period of time to reduce the TA level and keep it down, or just bring the TA and pH down initially and let it rise on it's own while aerating? When I first brought my pH down to 7.0 the TA came down to 70 but rose to 80 within a day or so. I didn't add any more MA until the pH got up to about 8.0.

Gary

 

[JasonLion]

It isn't necessary to keep the PH below 7.2, but it does speed up the process. Generally we recommend letting PH go up to 7.6 or so before lowering it again, but if you in a huge hurry you can lower the PH back to 7.0 sooner than that. All of this only affects the timing, not the end result.

By the by, the TA test is +-10, so a reading of 70 and a reading of 80 are the same and do not indicate that TA actually went up.

 

[dmanb2b]

Here is a pic of my aerator in action...about $5 of 1.5" PVC (pipe, 1 45elbow, 1 90elbow, end cap) screwed into my return. The showerhead is just a plain old endcap that I drilled a bunch of holes into. Really stirs things up and make the water fizz

 

[phalcon51]

Great idea!

 

[dmanb2b]

Wish I could take the credit for the idea, but someone else on TFP or Poolforum.com showed me the same...just figured I'd share since I've had great success using it. My fill water TA is 300+

 

[ChozPool]

My TA is a bit high and the Pool Calculator is telling me to add MA to lower the pH to 7.0 - 7.2 and then aerate to bring up the pH. I don't have any water features to aerate with, but I do have a small 1/4 hp, 23 gpm submersible pump from Harbor Freight. If I put the pump on a step just under the surface (to minimize pumping losses) and put a fan spray head on the end of the hose with it angled up into the air and falling into the pool, would that be a very effective aerator?

Actually, I just put the pump on the first step and turned it on with no hose connected and it shoots a column of water about 3-4 feet in the air before splashing back down into the pool. Would this be good enough? I'm trying to get the TA from about 110 down to 80-90. Any rough idea how long I might have to leave it running - hours? days?

The quickest way is to us a makeshift fitting on the return(s) and direct the water return higher than the pool level. Actually doing that as we write, since I had to lower my CYA by dilution. After lowering about half the pool and now beginning to refill via water hose (takes about 8 hours), just use the bottom drain to cycle the water while refilling. Returns were about 1/12' higher than the water level. Kill two birds with one stone.