Aeration's affect on water chemistry

[SunnyOptimism]

Does anyone know the affect of constant aeration on pool water chemistry? Specifically, does aeration affect free chlorine levels?

I have a new pool with an attached and raised spa. The spill way for the spa is 18" wide and the drop is about 2 ft or so. There's a three-way valve that controls the proportion of water that goes to the pool return jets and a return jet in the spa. I'd say about 2/3 of the water goes to the spa to run the spillway and about 1/3 goes to the three return jets in the pool. I also have a natural stone waterfall that I run a couple of times a day for a total run time of about 2 hours. The water fall is on a completely separate pump and piping system that is not at all connected to the main pool filtration/chlorination line (just a pump and some pipes pushing the pool water around). I can adjust the flow in the waterfall by adjusting a separate three-way valve that splits the water flow between the waterfall and a single return jet into the pool (designed that way for safety in case the waterfall line ever got plugged...keeps the pump from exploding ).

I typically run the spillway all the time (right now ~ 8 hours per day) and, as stated, the waterfall runs for about 2 hours (30min at pool startup, 1 hour at high noon and 30 mins prior to the end of the pool run).

Is constant aeration like this ok for water chemistry?

Some pool numbers -

Ambient temps (at time of post) - 100F +
Pool water temp - 80F to 86F
pH - 7.2 (it's a little low because I added acid and my FC levels are stuck until I get my CYA under control. I'm erring on the side of low pH to keep the HOCl levels higher than hypochlorite levels)
FC - 2
CC - 1
CYA - 100 (I know, it's way too high, I'm in the process of dumping water to lower it)
TA - ~80 (it's been rock solid all season between 70 and 90)
CH - 350 (I live in AZ, what can I say...tap water is typically 250+)
Salt - 3200ppm (salts a little low due to backwashing to lower CYA but SWG is not screaming at me yet)

Would love any pro-tips regarding aeration.....and wish me luck on getting my CYA and Cl levels back under control

PS - Anyone ever see the irony in using the acronym CYA (cover your a-- )for cynuric acid...kind of funny.....

 

[jblizzle]

Aeration should just raise the pH ... nothing else.

You should really keep your FC a LOT higher while you are in the process of replacing water or your water will turn green ... unless you are doing it in less than a day, but kind of sounds like you are doing it at a slower pace.

 

[Divin Dave]

+1 to what Jason said. Aeration will raise Ph, but wont have any other effects on the pool chemistry.

 

[SunnyOptimism]

Question about raising the FC value - is it ok to use liquid bleach to raise the FC while the salt generator is running? I'm currently running the SWG cell at 90% for 8 hours per day. I'm pretty sure that's A LOT of power and why I can actually measure any FC with all the CYA in my water but it's all I can do aside from adding liquid chlorine and I was concerned about doing that....just a newbie here so I don't want to go wrecking my brand new equipment by doing something stupid.

My CYA went up because I was an idiot and used my blue float with 3" tri-chlor pucks to try to raise my FC a few months back....dumb a-- mistake that I'll now be paying for with water replacement

 

[JasonLion]

Sure, just be sure to add the bleach by pouring slowly in front of a return jet, and do not add via the skimmer.

 

[SunnyOptimism]

Yeah, I'm probably going to do a "low & slow" method - 500 to 1000 gal every couple of days or so while monitoring CYA & salt levels.

I actually have two ways to purge water - standard backwash line (lots of volume and flow but it costs me DE every time I do it) and a hose bib and spigot that my pool builder left on top of the pump output (used during pool construction for filling and pressure testing the PVC lines). The spigot only gives me ~5 gal/min flow through a standard garden hose but I can run it for hours and the auto-fill in the pool should be able to keep up so the pool water level will hold stable. The second method saves me on the cost of DE and, because I don't have a lot of discharge space for the backwash, it saves me tearing up a patch of my yard with lots of high-volume backwash discharges.