Maintenance on 3d backgrounds and filtration

[Donny Brasco]

Before you say it yes i have searched..searched high and low for hours on end trying to get a straight answer but im struggling so i thought i would ask a few questions regarding what im wanting to do exactly.

So im planing on building a 3d background for my new display tank (some like them some don't, but i do) I will be going the polystyrene and concrete method which i understand how to do all this but this isn't the issue.

I want to "hide" my filter suction, outlet and heater as best i can which i have seen numerous ways of doing it but i wanted to know long term effects.

For example if you skip through this video

you will see how this guy has made channels in his backing to hide his pipes which i would like to do something similar.

In one of his later videos he mentioned he had trouble with bad build up of algae due to not being able to clean in there very easy.

So here is where my questions start.

1. surely removing the filter suction and outlet pipes and running some form of a small "dunny brush" if you will down the holes would be enough to clean some of the muck building up behind there and then just suck it up with your normal gravel clear would do the job correct?

2. I have always placed my filter outlets above the water level with spray bars to agitate the water, would mounting the spray bars vertical and below the water line to create a nice current be ok and then have a descent air stone or air tube hidden under the background as well to help break the surface be sufficient? or do i really need that filter outlet to break the surface?

3. cleaning shouldn't be to much of an issue as i wont be doing anything as crazy as the guy in the video so a simple brush of the background will be fine to get rid of algae growth but long term will the concrete loose color, become thin or break apart?

4. Everyone has mentioned that the concrete will raise the ph very high but a few water changes will settle this back down, are they talking about just doing say 3 or 4 water changes full to empty in the space of a week or 2 and then its fine to do my normal weekly change or will this ph increase be an on going thing?

Thanks in advance.