Problems keeping bubble coral, hammers, grapes

[fdnyhm1]

I have a 40 gal reef. Lighting: 2 - 150 wt 1400K HQI, 2 - 39wt actinic T-5 Calcium 420 Alk 7 dkh Ammonia 0.0 Nitrite 0.0 Nitrate 20 Ph 8.2 Temp 78
I just can't seem to keep bubble coral, hammers, or grapes.
Has anyone had this same problem or any ideas.

 

[xraydoc]

The only thing that I can see from your parameters is that the nitrates are not quite optimal, but also not so far off that I would expect you to have so much trouble.

Any chance you have some copper in your tank?

 

[gman0526]

Do they all "go" the same way? They just die or slowly fade away?

 

[guppychao]

nitrates are a bit high, also make sure that there is not too much flow as they get irritated

 

[Savas]

I have the same problem with all tanks. Mine just die slowly over a 2 - 4 month period. I have just chalked it up to me not being able to keep them and figure I can keep lots of other things.

 

[atzak]

Nitrates at 20 are not the problem, I've seen all the corals mentioned thrive at levels close to 100. What kind of fish do you have

 

[Aquabucket]

EDIT: Sorry wrong post.