Hi Dean,
I'd be inclined to agree with Lindy.
Your tank looks in a much better way than your previous algae outbreak so I'd leave it for a week or two with the spraybar configuration, some large water changes and good filter maintenance and see what happens....I know its not the best looking solution, but if it works you could look at acrylic which has been mentioned, or Apfuk now do glass spraybars 🙂 You know about maximising co2 whilst you have no livestock, (I know your keen to get some in but please resist for just a little longer) just get good levels for lights on. Personally I wouldn't supplement with liquid carbon as beating the algae without it will be far more valuable in learning about co2 light and distribution.
I think now there will be an improvement with the change in circulation as shallow tanks are more difficult to keep co2 in and perhaps the obubble lily was not getting flow to the substrate effectively. Your dc could have shown good levels of co2, however water movement through and over the grass could have been minimal which wouldn't have been efficient for nutrient supply and waste removal...either of which could have been a causal factor in the persistent algae problem. Grass is tight and traps detritus so flow through it is important.
Stick with it mate, things are definitely improving and I'm sure you'll be able to add some fish soon enough. If you need to dial back the co2 at a later date for livestock, and any algae reappears you could either reduce lighting intensity or supplement then with a little liquid carbon....but I'm sure the flow was your problem and keeping the grass clean will make the difference.
Cheerio
Ady