What am I missing?

cheap bulbs are no no.. atleast for the halides

your alk is probably 3 points off. alk is huge for coral growth thats something i didn't learn about for 5 years

 

Man I know cheap bulbs are the cardinal sin but they are so expensive. I am running 20k MH's perhaps I wil get more growth with 14k's? I also have to get my KH in check I guess just dont know how?

 

The biggest factor that I noticed, and 2in10 pointed out, is no Magnesium testing. If your Mag is low, you will have very slow growth.

 

If you are dosing, it's just a matter of slightly upping the dose per day. Your Kh isn't that far off where it would slow growth, unless you're not keeping up on your dosing and letting it slip.

 

OOps, sorry, I saw that you aren't dosing. That would be the problem. You have to do a lot of water changes to make up for not dosing, and you can't raise whatever parameter you want independently. I bet your alkalinity is varying.

 

Some people can get decent growth without dosing, but if you keep the magnesium, ca and alk up you would be surprised at the improvement over a couple of months. Since this is an established tank it probably has a good deal of coralline algae growth. Coralline like corals will suck up the ca, and trace elements. Sometimes you need to compensate for this with dosing.

Bad or old bulbs will slow things down considerably as well.