single vs double sided

[Aquaman]

I am flip flopping between a couple of UAS designs. One would be external, double-sided. The other would be in-sump, single sided. Both would use the same lighting and have the same surface area of material (2× 6x6 vs. 1x 6x12). My question is, is there any additional benefit to having a two sided operation vs a single sided with the same algae growing real estate, or are two-sislded builds simply more space efficient?

[SantaMonica]

2- sided is always best, because it keeps the roots alive longer. Strings are 2-sided too, and are probably the best way to make upflows. You could make a version of this upflow, with magnets, suction cups, or brackets:

https://www.youtube.com/watch?v=aGFhFtpEuR8