Hi there Phil,
I wouldn't add algaecide. You don't want those chemicals in your tank. The excess dead algae may work its way out of your tank via your upcoming gravel cleans and water changes or you may decide to replace your substrate after some discussion, but for now I'd hold steady and certainly not put any chemicals in.
While its true that all interior surfaces and objects will harbor some of our beneficial bacteria, its also true that the vast majority, and a sufficient amount, reside in the biomedia of the filter. That is because the filter provides a much better flow of ammonia and oxygen, the primary things the bacteria need. The problem in cases like yours is that since the tank has been let slide into a very dirty state, the gravel will kick loose a lot of debris each time its disturbed and since its a new tank you're not familiar with and has just been moved, its probably a good time initially to just give yourself a little time to get familiar with the tank and soon it will become obvious aesthetically whether you want to replace the substrate. Each gravel-clean-water-change you do will clear more and more debris and churn the gravel around, allowing you to better see what it will look like. Note that really dirty gravel will of course risk kicking up a mini-cycle, so you'll want to test to see whether a followup water change is in order (if it kicked ammonia or nitrite(NO2) to 0.25ppm or above.)
The very first thing to think about in the light changing plan is what approach to plant growing you want to take. Without going into too much detail, you have two broad options: low-light or high-light approaches. The dividing line is about 2 watts per US gallow if you are using T8 or T12 tubes. More wattage/light pushes plant growth, increasing their demand for all the nutrients they need. Carbon is one of their main needs and they get it primarily from CO2 which can be quite difficult to deliver to them underwater. Very roughly, this 2watt thing is an attempt at a warning that at some point the only way to keep up with this CO2 demand caused by all the light is to run an expensive setup delivering CO2 from a pressurized cylinder that looks like those that scuba divers use.
So all that long paragraph was a way to say that perhaps you'll be interested in the -other- choice of direction, for now, of choosing lighting -below- 2 watts, down in the 0.8 to 1.8 watt per gallon range. That way you can either not add extra carbon at all or can use a "liquid carbon" substitute product like EasyCarbo or Flourish Excel. And, by the way, all this is just to talk about carbon, which is only 1 out of the 17 main things these plants want, lol. But hopefully, this will have you aware of the key parameter as you struggle with actual hoods and hardware to fit your tank. Don't neglect the area of water condensation and having it drip back into the tank effectively.
Have you got a good gravel-cleaning siphon so you can be working on that gravel? You'll want to work the cylinder deep into the gravel, all the way to the tank bottom and let the debris flow out with the water that's begin removed. You can overdose your conditioner to the tune of 1.5x or 2x (not more I'd say) when treating the return water. Dose per bucket if that's how you return water. Dose per aquarium size if you are directly refilling via siphon or hose to the aquarium. If the change is above about 25% then it may be best to temperature match. Your hand is good enough to judge this.
~~waterdrop~~
