Both of these fish are very territorial and aggressive and grows with age and maturity. It will be a case of decided who goes or watch one die. Maroons are extremely aggressive and most like the Damsel will go.
What you have here is Grape Algae, A form of Macroalgae named Caulerpa. Its a very good exporter of phosphates and nitrates. Although a it is a great way to remove PO4 and NO3 there are downsides to it ability.
This algae can go sexual. What i mean by that is the process of the algae releasing all the absorbed PO4 and NO3 back into the water column causing havock.
It must be kept under 24/7 lighting to avoid this.
Also adding, it can grow fast, upto an inch per day! You have a small amount so try to separate the rock(s) that it as rooted too, as this is a weed. If there are roots in the rock it will grow and take over.
Just for your future reference. To check that it isnt going sexual just look at its colour and texture. If it look like a very very pale lime green remove it. Also if it feels soft and squishy remove it, as it should be firm and relatively solid.
ok, first of all get a TDS meter to check its not your RO, saves you spending money you dont need to spend. Do you have a DI with the RO unit?
Because you have fitted a sump to the system, it may have upset the bacteria a little thus causing a Diatom bloom, these will alway come and go and take from a couple of weeks to a few month to clear... i know i looks ugly but we have all had it... im going though one now and its been around for a good month...
Yesh that ro unit is fine, make sure though you have the DI canister with resin as this is the only way to get TDS down to zero
Sorry tony and Mike, but im still not convincned it a 'nem... the one on the right looked to have a tube like object from where it is pretruding... as does the one on left but be coz of angle you cant see it as much....
Could you get a piccy that closer up and/or from the side?
i think the second picture is a species of tube worm... if you can light brush them with something and they retract they are defo tube worms, ive got a few of these in my tank and very sure that what the second piccy is showing