Well, here's the math. If you run the LQ at 5cc/min for 12 hours that equates to about 121oz of 6% chlorine per day which in turn, equates to about 2.3ppm per day of FC in a 25,000 gallon pool. That's very possible to do but it doesn't give you much leeway.
You'd also be filling the LQ every 8 days or so.
If you always use 12.5% it would give you more leeway and longer time between fills.
With a pool that size I'd take a hard look at a peristaltic pump and tank system. You can get them up to 30 gallons and whatever flow rate you need to maintain the FC.
Don't get me wrong, I love my LQ but I don't want to recommend something borderline which in your case I think it would be. You could however, buy two LQ's for less than a tank and pump system and run them parallel if one wasn't quite enough at times. Just food for thought.
Hey Bama: is the LQ 5cc/min rate the maximum for a 1.5 HP pump? Using 12% seems like a good option. If one could get a greater feed rate than 5 cc/min, and even if the LQ had to be filled every 4 days that may be worth it, in my opinion - especially if peristaltic/storage tank system is more than double the cost of a LQ.
My pool is 24,000 gallons, and I have switched to 12.5% (I find it is cheaper than buying the 6% ). I'm holding 4-5 ppm with the flow valve cracked about 2/3 the way open (I have removed my flow meter, since I check my FC daily and don't really need to know where my flow is), and I have the 3/8 upgrade. I add 1 gallon of chlorine about every 4 days to keep things where I want it under current conditions (we haven't really gotten the heat yet, so the days are in the 80's, and my water is at 84 degrees).
I think that pools in the 30,000 gallon and up range would probably not be good LQ candidates, but I have no troubles keeping mine supplied (and my pool is 100' away from my equipment, for whatever that is worth!).
The LQ's flow meter only reads to 5cc/min so that's the reason for that number. I can get 5+ on my meter so it's possible to get more than the max flow shown on the meter. If you use 12.5% as Bruce does you'll be able to get plenty of flow and it'll last a couple of weeks between fills. Removing the flow meter will actually help the flow because it removes some restriction.
A pump and tank system is going to cost about 3 times as much as an LQ.