Correct chemical levels for my system?

[MichaelJSullivan]

Hey all, I'm starting to get a handle on things but I'm still learning...I think I have a fairly complicated system (brand new) and I want to get my levels correct. I should say that my water is crystal clear, free of metals, and has low hardness (comes from a well) and is always at 7.5 pH. Here are some specifics on my system.

• Variable speed pump that runs at a low RPM 24/7
• Sand filter
• SWG for converting salt to Chlorine
• UV/Ozone system as a secondary sanitation system
• CO2 system to balance PH
• ORP system that regulates everything.
• Pool usage - mainly just 2 people (me and my wife), daily but for an hour or so.
• Pool size 38,000 gallons.
• Pool location 100% full sunshine in the Shenandoah Valley of Virginia.

So now the questions:

• What CYA level should I have -- From my readings here SWG pools should have a higher CYA than a non salt-water using direct chlorine - but I think I also saw somewhere that ORP's don't work well at higher CYA's so what should I be at?
• TA - what should it be so that the PH doesn't fluctuate too much
• CH - does this matter at all? My pool store says I need to make my water harder (because all chemicals affect each other) but while I think hard water can be a problem, soft water shouldn't be (after all people with hard drinking water add systems to soften them but I've never heard of anyone adding something to harden their drinking water.
• One last question, my pool company says I should shock once a week - but that makes no sense to me. My system is trying to keep everything nicely balanced and should have plenty of disinfecting power to keep everything clean...and as I said it's crystal clear and seems very comfortable (no burning in eyes or skin) so dumping a ton of chlorine into a system that is trying to keep chlorine regulated seems like it would throw off everything, yes?

 

[needsajet]

Welcome to TFP! Good to have you here

Weekly shocking is not a good practice, and should not be necessary.

We'll need to know your type of pool (plaster, vinyl or fibreglass). The handiest way is to include a "signature" (see mine below). There's instructions for doing this in "read before posting" linked in my signature. In the meantime, here are the recommended levels for balanced water: Pool School - Recommended Levels

With ORP control, keep CYA low (<30) to slow down ORP sensor fouling. Be sure to get a FAS-DPD test kit so you'll know when the ORP sensor gets fouled. Lower than ideal CYA will indirectly make your SWG cell wear out faster because it has to run longer, but otherwise the pool will be safe if an adequate FC level is maintained, per [FC/CYA][/FC/CYA]

That said, even a small amount of CYA provides a fair bit of UV protection. The problem is testing and knowing if you're at 0, 10 or 20 ppm. The CYA gets depleted by splashout and backwashing, so eventually you'll need to test, and the available test has a minimum of 30 ppm.

Do you have both UV and ozone? Is it a combined unit? Chlorine is all that's needed for an outdoor residential pool, so you can turn those off if you like. Ozone also depletes some of the FC, so turning it off will indirectly extend the life of your SWG cell. UV light from the sun is vastly more powerful than a residential pool UV system, so turning that off will save a bit of power.

TA at 50 and above is usually adequate. You'll see 60 as our minimum which provides plenty of buffer to guard against a rapid pH drop.

Soft water in a pool, or better said, water with inadequate hardness, can lead to plaster etching. So yes, water balance matters in a pool.

When I started out with TFPC, I gained a lot from this article. There are many ways to look after a pool, and the TFPC system is based based on effectiveness, low cost and simplicity. TFPC for Beginners

 

[cfherrman]

Burning eyes is from pH inbalence

Burning skin is from too low of clorine creating high cc's