Hey! What can I do to get rid of this brown algae on the sand??
Also, would a ruby red dragonette clean my tank?
It looks like the start of the ugly phase. That brown stuff is either cyano or diatom, Its not harmful, just syphon it out with your water change and keep it up. It will go away naturally in a few weeks to a month but you will go thru a few rounds of this as yiur tankbstarts to mature.
Do not add any more biological control to try to specifically deal with this bc remember this is temporary so whatever you get will starve when this goes away
I don't remember what CUC you have - if you have none, then may be a few snails will help. Id start with 2 nassarious to stir the sand, 2 - 3 cerith as general grazer, and 1 - 2 trochus as the power hitters. Do not get a giant turbo yet, your tank may not be mature and diverse, or big enough to handle such a huge and hungry eater.
There will be turnover death rate in the snail, so if you see a few die, do not try to replace right away - dead snail usually means there's not enough to eat and they are starving. Since the "death rate" often lags behind the algae replenish rate, my general rule is to replace 1 for every 2 deaths to help get to the equilibrium of snails that a tank can maintain long term.
For flow / gph - is everything happy?? If so then its best to not mess with it since for young tanks you dobt want to changs too much too fast. There are guards you can buy if you are concerned about nem getting stuck in them. If you feel like you need to change flow bc something is not happy bc of flow issues , then keep reading.
i don't recall what ur current GPH is but what's ideal depends on what your currently have. I don't really subscribe to a "multiple of volume" ratio bc the type of current and water movement is more important that the volume and speed of it. Thats why you have such a wide range of recommendations as some say 10x to 20x and yet some tanks have 50x to 100x. I look at these below factors:
1) is my current above the sand strong enough to prevent too much detritus from settling? Generally diatom grow in low flow areas so those brown spots may indicate too little flow there.
2) are any of my corals struggling to open because current too strong? Zoas can tolerate different ranges but their shape will change. High current is often linked to "long and hairy" polyp tentacles and low current gives the typical "cute and stubby" tentacles thats typically associated with zoa.
3) is the Nem happy? They usually prefer high but random flow. This may be more difficult for your tank to achieve depending on how fluid dynamics interact with your rock work and if you can create high/random zones as well as low zones for the zoa and moderate/high circular current for the sand surface.
Checking off all the boxes above is not easy, or may not be possible depending on the rockscape. The best luck i had when using hydors on my small 20G was a couple of 240s going in diff directions to customize the flow. What you'll want is for 1 head to create the backbone circulation to keep all the waste suspended so it can be picked up by your overflow box on top, then a second head that intersect the main current to create randomness in sections that wants it, and create "current break" zone for low current corals. Then I set one of the pump on timer so it only goes on during the day so that current is lower at night to help fish rest.
There's no exact science here. A lot of trial and error. And doesn't need to be perfect - adding a couple of rocks here and there to modify the current is fine, but don't go tearing up ur whole structure if you cant achieve exactly what you want.