ATS Crashed Now What! Help!

I have a DIY ATS on my tank. I was doing my weekly cleaning and removed a ton of algae for a year and a half. Life was good. The tank has been looking great and I have been scraping large amounts of algae off the scrubber every week. I put everything back together and walked away. The next day, approximately 24 hours later, including on full 12 hour phototherapy session, I realized that I never turned the flow on to the scrubber. I immediately turned the water back on but it was bone dry. The water has been running for about 5 days now and the screen has white slime on it but no algae. Luckily I am in the middle of TTM with a new fish so I am doing constant water changes.

What should I do about the scrubber? Should I figure out a temporary method of nutrient export or just stick with water changes and hope the scrubber comes back quickly? Should I lower the flow or increase the photoperiod? Should I clean the screen or let it go for a few weeks? How long should it take to come back?

I currently have the 6x4 scrubber lit on both sides with 8 660nm LEDS and 2 rb LEDS running at 700ma for 12 hours on and 12 hours off.

Also I noticed that the screen is no longer rough from all the scraping and cleaning. Should I rough the screen up again?

It's just going to have to start back up again, as original. It might be a bit quicker, but probably the same time. 12 hours is fine, and just use the screen you have.

I got the scrubber back up and running with some growth. Not as much as I would like and there is hair algae in the tank from when the scrubber was coming back up. I haven't harvested the scrubber yet. I am wondering if it is a flow issue. I have no real way to calculate the flow rates that I have right now. The scrubber is running off the overflow and it has a valve that i can use to control it. The screen is 6 wide by 4. I need approximately 210 gph according to the calculations (35 x 6). I created a new slot pipe as my old one had a large slot.

I cant decide if the slot is too big. I also cant measure flow rates as it drains into the sump and if i plumbed it to drain out of the sump, the sump would drain quickly.

I do know that my return pump (Rio 3100+ with 4.5 ft of head) does not reach my emergency overflow unless i throttle the valve to the scrubber back. Is it better to have a bigger slot and throttle with a valve or a smaller slot and control the flow with slot size? Could too much flow stunt the algae growth?

With the bigger slot, if i throttle the valve to slow the flow, I get alot of water on one end of the screen and not much on the side closest to the supply. If i throttle down to get an even coat of water over everything, the water exposes algae and parts of the screen as it is too little flow. If there any way to dial this in better?

If the slot is 3mm wide for a single sheet of screen, then it will fill in with growth and the flow will even out. As long as the bottom of the screen has a solid flow of water coming off it all the way across, it is ok. Too much flow will not hurt.