A couple of questions from a new pool owner

[supermoof]

Hello,
I recently moved to a house that has a pool. I'm attempting to take care of the maintenance myself, but I have a couple of questions.
First, The pool had noticible algae on the sides a couple of weeks ago. Nothing on the surface as far as I could tell, but a green looking substance on the sides of the pool at and below the water line. I brushed off what I could, and used some algaecide and shocked the pool to 30ppm (using 3 gallons of liquid chlorine for my ~10,000 gallon pool). The algae came back the next week and so I did the same. It's been about a week since that and there is nothing noticable, but I have noticed that my chlorine levels are dropping. From shocking the pool with 3 gallons a week ago, today the chemicals are at:

1ppm Free chlorine
0 Combined
ph 7.4
Alkaliniy 100
Calcium hardness 350
Cyanuric acid 32

I added more chlorine to bring it up to ~5ppm, but it seems like the levels are dropping quickly. I'm in Austin, TX where it's been in the 80s for a while so I suppose it is natural for the levels to drop quickly, but how much chlorine should I expect to have to add per week? In addition to adding liquid chlorine I have an in line chlorinator that has a couple of 3" tablets in it. My question is whether this amount of chlorine loss is normal, or whether there is still algae in the pool eating it up. And if that is the case, what other steps should I be taking and how do I know when it is gone for good?

My second concern is that when I turn the pump on, it pushes a lot of air out of the returns for the first 30 second which causes the water to bubble up and spill over the edge. There appears to be a leak on the lid of my chlorinator so I've ordered a new o-ring for this, but the leak seems fairly small. What could cause this much air to build up in the system when the pool is off? And can it cause damage when it's pushing this much air through the system? As far as I can tell everything other than the chlorinator seems sealed well, the filter isn't leaking and the pump itself seems fine.

Thanks so much!

 

[JasonLion]

Even a very small air leak will allow all of the water to drain out of the plumbing while the pump is off. Then, when the pump comes back on it takes a minute for that air to be flushed out of the system.

Please take a look at the instructions on how to shock your pool in Pool School.

 

[PSW]

Welcome to TFP!

As Jason said above, you should familiarize yourself with the shocking process in pool school. My guess is..that each time you 'shocked,' the FC was not left at shock level for long enough. During the shock process, you should be checking your levels at LEAST once per day (ideally more often), and adjust accordingly. Also, you have to shock until you pass the overnight chlorine loss test (lose less than 1ppm FC overnight). It sounds to me like you only shocked until pool appeared clear.

About losing FC...this could be due to an algae bloom (but then you would be seeing some CC). It could also 'burn off' because of low CYA. Although 30 is within the target range, it is the lower end. You could raise your CYA to 40 or 50 and that would help you retain chlorine. If you do this, you will want to maintain FC of 5-6ppm. This will prevent future algae blooms (provided you shock the pool correctly first).