Transform HOB filter to Refugium?

So I have this HOB Aquaclear 70 that I inherited with the tank. Currently all that I have in there is a sponge and a bag of carbon I bought when I started my tank.

Now I am having the typical Cyno and just general Algae bloom. I plan on cutting back my lights more. And I dont feed much but I only have 2 fish so I will start feeding only every other day.

So the question is. I dont know what I should have in the filter area. Some Ideas were:

Filter bags with PhosBan (I guess the popular brand?)
Filter bags with Carbon (any particular type?)
And leave the sponge.

or

I have seen mods to it where you put cheto or some other macro algae in there and it becomes a Refugium.


Also as a sub question as your looking at this. Should I continue to wait on getting soft corals till I can control my Cyno and Algae problems? Or could their addition help with balance in the tank.

 

You may want to add more cured LR. I don't think 30lbs is enough for a 45g. Also you need more flow in the tank. If you use any filter media it should be cleaned weekly at the least. If you don't clean the media it will result in high nitrate and phosphate levels...which means algae. I would recommend:

Feed fish- every other day
more flow
more LR
clean out filter media regularly
regular water changes
testing your water perameters

if you post more info, such as your test results, how long the tank has been set up, we will be able to help you better