Why does aeration increase ph

And it is not a precipitate that is easily removed. In addition, the high pH can cause metal staining if metals are in the water. If there were a chemical that strongly precipitated carbonate without forming scale, that would be great similar to the lanthanum based products that precipitate phosphates for algae control , but there isn't any. The best way of removing the carbonates in the water is to aerate the water to remove carbon dioxide CO2 since the pool is over-saturated in the first place.

Lowering the pH significantly will increase the amount of carbonates that are in the form of carbon dioxide in the water and that will increase the rate of outgassing carbon dioxide leaving thewater. Aeration will also increase this rate of outgassing. As the carbon dioxide outgases, the pH rises with no change in total alkalinity.

In other words, add acid until the alkalinity reaches about 90 to ppm. Then aerate until the pH rises to 7. The main rule to keep in mind is that it takes The problem: If one adds enough acid to lower the total alkalinity all at once, the pH can get very low. Now, let's see how low it would actually go in some extreme cases.

Case Study For this example, assume there are no borates, the cyanuric acid is 30 ppm and the pH is starting out at 7. If one lowers the total alkalinity from ppm to 80 ppm, the pH would drop to 6. If one lowered the total alkalinity from ppm to 80 ppm, the pH would drop to 5. So you can see that even extreme additions of acid to lower the total alkalinity, at least to 80 ppm, don't get the pH much below 6. While such a pH is not good in the long-term, having the pH at that level for a relatively short time — less than a day — is not a disaster.

At such a low pH, carbon dioxide will be driven from the water fairly quickly since there is to times more carbon dioxide in the water as the equilibrium amount with the air above the water.

Add the Acid The key to adding such large quantities of acid to the pool is to avoid overdosing in one place, as that could damage the plaster. Adding the acid slowly over a return flow with the pump running, and then brushing to ensure thorough mixing, will prevent the pH from getting too low in one spot, potentially damaging the plaster. And obviously, one doesn't want a return fitting pointing up when adding the acid because you don't want it splashing back at you.

Add the Air Simply doing things like pointing the returns upwards and running the pump on high to create surface disturbance will aerate the water reasonably well. One could also add an aerator to a standard return.

If there are waterfalls, fountains, spillovers, etc. Even better: an air compressor with a head that has many tiny holes. Upload or insert images from URL. By drewskie Started December 31, By sweeperq Started Tuesday at PM. By FromFargo Started August Share More sharing options Followers 0. Reply to this topic Start new topic. Recommended Posts. Gavin Posted March 11, Posted March 11, If you take a wander over to chemistry there a a few threads about pH and areation. I'm sure chem geek will be along and give you the short version but you can use the Google search function at the bottom of the page if you'd like to read it on your own.

Anything that increases the surface area of the air-water interface will increase the rate of carbon dioxide leaving the pool water. Aeration, as with air bubbles in water, is one way. Splashing or spillovers or fountains are another. Pools are intentionally over-carbonated both to provide a pH buffer and to saturate the water with the carbonate portion of calcium carbonate to protect plaster surfaces from dissolving. In other words, there is a lot more dissolved carbon dioxide in the water than would naturally occur in equilibrium with the air though obviously not as much as a carbonated beverage!

As for why the pH rises, the easiest way to explain it is that some of the carbon dioxide in water is carbonic acid -- that is, carbon dioxide plus water makes carbonic acid -- so removing carbon dioxide is like removing carbonic acid.

Removing an acid from the water makes the pH rise. One of the posts on this subject with the chemical equations is here. Your saltwater chlorine generator, however, may also increase pH through another mechanism in addition to the increased aeration from the hydrogen gas bubbles. The chlorine gas itself may not fully dissolve in the water.

If any escapes without dissolving, then the net result is a rise in pH since the net neutrality in pH depends on the chlorine gas dissolving in the water to form hypochlorous acid, which is an acidic process, and on the chlorine getting consumed either by breakdown in sunlight or oxidizing bather waste or other organics, which is also an acidic process.

More chemical details about this are in this post. Reactions: DLip. You must log in or register to reply here. Thread Status. For clear and comfortable water, your pH needs to be between 7. The total alkalinity controls how easy or hard it is for you to adjust your pH levels.

If your total alkalinity is too high, your pH level will be almost impossible to change. If your total alkalinity is too low, your pH will be very volatile. How do you raise alkalinity and lower pH? Use an alkalinity increaser like sodium bicarbonate to raise total alkalinity, or an acid to lower it. When using high-pH chlorines like liquid bleach or Cal Hypo, stay lower in the range, like ppm. For low pH chlorines like Trichlor, ppm is where you want to be. How much acid is needed to change the pH of water?

Diluting acids and bases To make the pH change by 1, a tenfold dilution is required eg adding 9 cm 3 of water to 1 cm 3 acid. The acid is becoming less acidic. Why is pH important in wastewater treatment? Determination of pH plays an important role in the wastewater treatment process. Because it is such a critical component of the makeup of the wastewater, it is therefore critically important to treatment.

How do you treat high pH in water? Acid injection treats water with a high pH by lowering the pH of water to around 7, which eliminates the soda taste and can improve the effectiveness of chlorination.