what is this on my new watermellon mushroom

[newbytomarines]

There a white circular thing with what looks like 10 r so white legs, does anyone know ehat is is? Have thevcoral less than a week and it is growing by the day so dont think it killing it, just would like to know what it is thanks

 

[mr_X]

It looks like a hydroid on top of some cyanobacteria.

 

[newbytomarines]

Is that good r bad?? Thanks for getting back to me, all my corals and invertebrates are doing brill, however all my fish r getting white spot and r dying I have lost 4in the past 2weeks, only 2fish left which have whitespot, sometimes this hobby can get hard, doing water changes everyday, is there anything else I can do??

 

[mr_X]

It's been my experience that fish succumb to diseases and parasites like ich when they are stressed. Something about the tank is not agreeing with them. What are your current parameters?
How are you doing your water changes exactly?

As for the alleged hydroid, as long as it's not hurting anything I would leave it be. Just watch that it doesn't multiply too quickly. Then you'll have to consider killing it off.
the cyanobacteria is brought on by excessive nutrients. When you are doing your water changes, vacuum that out. Watch your feeding.

 

[newbytomarines]

I take out 25lts weekly from a 128lt tank, and topoing of with ro water when needed about 3times a week,
Everything is sitting at 0 and my ph is 8.2 ans saltinty is perfect,

I do agree I might be overfeeding, they get fed once a day with either dry or frozen food and I will feed the corals every 2days a capful at a time, and I would give them dry seadweed every 2days aswel, is this too much

 

[mr_X]

Well, I would say yes, since there is cyano present. What are you feeding the corals? You can completely skip that for starters.

water changes- I mean, do you mix the water overnight with a heater and powerhead? What is the procedure?

 

[newbytomarines]

I got a green bottle of liquid that my lfs said was good for the growth of my corals,
I get my saltwater already mixed and it b sitting at room temp, the shopsaid it b fine to put in straight from drum,

I went to a shop and got a baby dory fish type of tang, they didnt tell me it b too big for my tank, it got white spot first and then the rest got the white spot so I think the stress from that fish caused the rest of my fish to get it too

 

[mr_X]

You want to keep your water moving/aerated if you are storing it. The ph could vary greatly from the tank water if not.
As for the green liquid, you can stop that immediately. I imagine this is phytoplankton, and unless you have non-photosynthetic corals like gorgonians, you don't need it.