Set up basics

Hi, I'm just getting back into the saltwater tanks, have a 20g tank with 2 clownfish, 4 soft corals, snails and hermitcrabs.
My apologies in advance, as I'm sure this has been covered here before but since I couldn't find it, could someone help me with the basic set up of the tank. I have a good pump (iheimer 1500), skimmer that has stopped skimming after I've cleaned the water 2 weeks ago and didn't restart after I've changed water again a week ago, LED coral capable light - only half of it is working but a replacement is on the way, heater and filters.
My fish "seem" to be doing ok, but the corals looked much better in the store. I'm going to find out and write down their names, but if anyone can tell by the attached picture what's wrong with my set up it would be SO helpful: do the corals I have need a lot of light, flow? I do feed the one on the bottom...
I read in a thread that one needs a doser and that made me question my tank set up: other than a doser what else do I need for a good coral-friendly environment?

thanks!!!

 

Really hard to make out the corals, sorry.

I believe the one to the right in the sand bed may be a Green Star Polyp (GSP).

The one mid way in the rock work maybe a zoanthid or palys, could be a mushroom I suppose.

For those types of corals and the age of your tank, you do not need a doser nor should you dose at this point. Mod to lower lighting for the GSP and possible palys or mushrooms.

If you can get a better image of the corals, that would help.

The ones up top I have no idea need a much closer image. Try getting much closer to the corals and using the macro image option on your camera or the focus.

 

coral pics

here are some close-ups of the corals: the first one has some grass growing, I suspect that it's some sort of algae and have tried to put hermit crabs on it, but they won't eat that one, ate everything else off it.
second and third pictures have the close ups of the 2 corals on top. they are on one rock and there is something weird, film-covered on that rock as well, don't know what that is and what to do about it.
the forth one shows the mashroomy things.
and the last one is of the "star-dust" that I feed every 2 days.
Quiet a puzzle to me!

 

1st. Zoas(not sure what kind)
2nd GSP
3rd looks like goniporia.
4th Button polyps
5th Torch coral

 

I agree with this ^

Do you have a test kit to check for nitrates, phosphates, KH, ect?

Also what is your salinity at?

 

the 1st image looks like zoas getting killed by possible GHA
2nd image looks like GSP that are doing fine
3rd image is a flowerpot coral in pretty good health even though they are hard to care for
also in the 3rd image looks like an aptasia pest anemone to the right of the flowerpot
4th image are button polyps or palys
last image could be a galaxea coral

 

Thank you so much for the IDs!
Now I'm really worried about the 1st one. If it is Zoas and something is killing it, any way I could save it?
And, is the aptasia pest anemone bad?
My salinity is at 35 (haven't checked it in a couple of weeks and didn't realise it was getting close to the end of the good range) - does it mean I need to add some salty water. I buy the water at the LFS and was hoping all the levels should be ok...
As for the last image, I do believe it's galaxea coral. Should it be happy without too much light, about 15in away from the light?

 

Well it depends on your reading. 35 PPT is around 1.026 salinity and is right at the max upper end. I run my tank at that level constantly. Salt does not evaporate, where as regular water will. If you add more salt water, that salt will be in addition to the salt already left behind from evaporation and it will just increase the salinity beyond livable conditions for anything in your tank. You need to add fresh top off water (water without any salt, but still purified). That way you can maintain a constant salinity level of 1.021-1.026 and everything will be happy.

Also you should be doing water changes much more often than every 2 weeks, especially since you said your skimmer is not working. 20 gallons is not a lot of water volume and waste build up quite fast in that small of a set up. Try doing a 20% water change once a week. Without a skimmer and water changes Nitrate, as well as Phosphate (PO4) will build up and end up killing most life in the aquarium. It also is the cause of your algae problem. LFS water, while not the best, often times is fine especially with what you are keeping atm, however waste does accumulate via fish poop and feedings ect. and that is what you need to be exporting via water changes.

Which leads me to say, you can save those zoas IMHO, they don't look too bad yet. Just clean up your water quality and maintain a constant salinity. You should also, if you have the ability to, remove as much of the hair algae physically from the tank as possible. Your other stuff should all do okay under the amount of light you have, but the waste levels will really determine the final outcome.

 

1. Zonathids: Easy to keep, and you do not need to feed them. They grow pretty fast in good conditions
2.GSP: Very easy to keep. It will grow like crazy if it is happy. Does not need to be fed. likes medium-high flow.
3. Gonipora (Flowerpot Coral): Very difficult to keep, and it be fed phytoplankton and brine shrimp daily. For a newer system such as yours I would highly reccomend to bring this one back to the LFS. It is not impossible to keep, but it is very challenging to keep alive any longer than 6 months-1 year.
4. Some type of Euphyllia (A type of LPS coral), but I am not sure which. It looks kind of like a torch. It should be fed brine shrimp one a week. It is not the easiest coral to keep and it is not the hardest coral to keep. Look some of the coral names up on google to see some more of the general care requirements.
JJL