dlandino

What's your Ca and how old is the system? When alk or Ca are out of whack, they can actually work against each other. IMO your alk is a tad low and even though your PO4 is testing at none detected (not 0), I bet you have some PO4 in there. Access to a phosphate meter would answer that. Kalk dosed in your skimmer does a pretty good job on PO4. A dirty skimmer can be a PO4 culprit as well.
Some have reported elevated Mg levels (above 1500) can impact HA problems. I would bust out the old toothbrush and scrub some of those problem areas like that clam, and pick out the tufts where you can. For small to med sized softie and LPS colonies, you may want to read about hydrogen peroxide dip. It's 9/10 tank water and 1/10 peroxide, dipped and basted for 10 mins. I've had some great luck with that.
IME, clams (like your T. maxima) generally like high flow, don't be afraid to boost your flow rates, it will also keep detritus in the water column and off your clam.

Thanks very much for the response. I did neglect to leave out my calcium and mg levels. Sorry about that.

Calcium 460
Mg 1420 (last tested abut a month ago. I will rerun the test today)
My skimmer is completely cleaned out every week. I actually run a vinegar and water solution throught he skimmer while in a bucket in my sink for about 20 minutes while I clean the rest of the tank. I am going to boost my flow tonight to see if it makes a difference on that problem area. Do you think this is a Bryopsis though? The notion is scaring the heck out of me. Thanks again.
Dave

Hard for me to tell if it is Bryopsis, it's just general HA to me. Large Turbo snails, growing macro and dosing for Mg seem to keep HA in check for me (knock wood).

Doesn't look like typical Bryopsis, but it doesn't really matter. Try attacking it with tweezers and a toothbrush to get it under control then perhaps install a phosban reactor. That really did the trick for my algae issues. Persistence will pay off eventually.

Thanks SeaPug, as you were typing this I was already scrubbing and tweezing. I would say that I was able to remove about 3/4 of it with those two methods. I don't runa reactor becasue I don't have a sump. My deltec mce 600 does however have a media chamber in which I run the following. Puirgen, BRS Carbon and BRS High Capacity GFO. I am going to step up my water changes and I have added tonight another 800 gph in flow. I'll update this thread with my progress. Sound like I am on a good track with these first attempts?

You bet! Your maintenance sounds pretty solid.

that pic is hard to tell
might want to stock up on some tech m just in case
i have dosed it before by turkey baisting it right on the bryopsis

Update on this: It is in fact bryopsis and I have been "treating" with Tech M with fantastic results. There have been some side effects to report. My zoas are browning out pretty badly and my encrusting and plating montis are showing some signs of reduced pe and stress. On the flip side, the bryopsis patches are about 90% gone and what is left isn't looking too hot. I am prepared to lose some corals to this treatment but if it means that I have halted bryopsis it is worth it.