Calcium Reactor can't keep up

[referinohio]

I have a Blue Aquatics Calcium Reactor and the best
I can get out of this thing is 340 ca. And 10 DKH.
It has a 4" x 18 reactor chamber.
Running effluent wide open with a PH of 6.3.
Is this just too small for a 125?
Seems like I used to be able to maintain decent levels with it but I do have some rather large LPS corals and a bunch of SPS (only frags though) 
Thanks

[CoralBeauties]

I wouldnt want to go any higher with your alk.  From previous reading a reactor is not good at raising the levels but for mostly maintaining your levels.  bring your ca level up to 400 or so and see how well the reactor keeps up.  I would think that if most of your corals are frag size your ca consumption shouldnt outpace your reactor.  Also are your water changes done with a quality salt with good calcium levels?
Jeff