I think your coral problem lies with your starfish, it eats coral for a living
Your test kit is probably a little old or reading incorrectly. If you are keeping those fish alive and the tank is established, you probably(
) dont have ammonia... probably....
Try: zoos, mushroom(no yuma or ricordea just the normal flat ones.. like disocoma or rhodactis), leathers(toadstool or kenyas).
all of these corals are 'almost' bulletproof. If you can keep an anemone, you should be able to keep a mushroom! you can pretty much place these corals anywhere in your tank. Maybe not RIGHT under the light.. as it may be too bright. lower light, and lower flow will make these corals expand larger.
I skimmed your other thread and you definitely need more flow in that tank. The importance of flow is that any detritus(crap, leftover food etc) will accumulate on your coral and will basically rot the coral or cause infection. It is important to get a powerhead and place it about 2 inch from the surface .. and point it at the surface so it is making like little waves. The surface agitation will help you get the filmy stuff off the top of the water and make it easier to filter it out, also it allows for better gas exchange.. and it makes a nice shimmer effect on the sand floor(since you have metal halides). then get another powerhead and put it in the lower half of the tank. you may need two pointing in opposite directions. Most reef tanks require a medium, turbid flow (multidirectional) I recommend the koralias. I have two koralia-nanos in my 24g and they are great and easy to work with. You can get them for like 20 bucks or so. I know you said you have powerheads but I think you need more or you need stronger ones. I had a 44g hex (the next size up just like yours) and the flow was VERY difficult to get right. The slime algae is directly affected by the lack of flow (and too much nutrients..)
Make sure you are using RO water when you make saltwater. and also do your topoffs with RO
Most people over feed, dont worry about it. I over feed like crazy. But, if its really out of control, keep your waterchanges up and also maybe get a better protein skimmer to pull some of the extra protein out of the water. is your skimmer pulling scum out of the water into the collection cup?
you could also get some sea grapes (plants) like caulerpa that you can keep in the tank and they will eat up alot of the nutrients which means the algae wont have any to grow! also, the plants look kind of cool, and they are available in all kinds of colors.. Ive seen red, green and BLUE!
What spectrum is your bulb (meaning .. what color does your bulb look like?) is it crystal white looking, or bluish , or yellow when you turn it on? (not the actinics.. just the halide). Certain spectrums will provide better growing for algae. The algae will grow fast if your bulb is old, or is in the 6700-10000k range (yellowish color when it lights up). Getting a bulb with a higher kelvin (color temperature) like 10000-20000k will look nicer and lessen algae growth.
how long are you keeping your lights on? to help kill the algae faster.. lessen your photo-period to less hours per day for a week or so, your critters will be fine, but the algae wont.
are you dosing any chemicals? Im not a big believer in chemicals but Ive been using a 2 part doser for about6-8 months and all of my levels are constantly perfect. In my opinion it can be VERY hard to stabilize your ph level if you are over feeding, and sometimes you may need to add a buffer or something when you do water changes.
I dont know how much this helps. I hope someone lives near you that can assist you! Try this stuff out, or tell us a little more about your setup/habits.
Good Luck!
Jess
ps. what type of anemone do you have and how long have you had it?
do you have pics of your tank?