Many people with larger tanks want a single, larger size algae scrubber. Probably because it seems simpler. And it certainly is cheaper. But when the focus is more filtering (not more pods), it's better to have two or more smaller scrubbers instead of one larger one. This is because scrubbers only filter when they have algae growing inside, and if you clean/harvest it completely, there is little filtering for a few days until it grows back. And cleaning/harvesting it with freshwater in your sink will kill many of the pods that will otherwise eat your algae, thus increasing filtering more.
It's certainly possible to only clean half of a scrubber, or to just partially harvest it. But for higher nutrient water, cleaning all the way down to the white Green Grabber® rocky surface on a HOG, DROP or SURF model, or the white Green Grabber screen on a RAIN model (including inside the screen holes), helps the white surface reflect more light back to the roots of the growth, allowing for more days of attached growth to occur before it lets go.
If the focus instead is more pods (and not more filtering), then you want to leave as much growth in the scrubber as you can, for as long as you can, and clean/harvest it minimally so that the pods grow and multiply more. So multiple scrubbers are not needed. And in saltwater, if you can clean/harvest with saltwater (or just harvest in-place without removing the scrubber), then you will have the most pods possible for feeding. Pods also occur in freshwater tanks, but less so.
Here are two HOG3 units which have strings for saltwater; for freshwater you don't need the strings, and a HOG2 or 2x is fine:
It's certainly possible to only clean half of a scrubber, or to just partially harvest it. But for higher nutrient water, cleaning all the way down to the white Green Grabber® rocky surface on a HOG, DROP or SURF model, or the white Green Grabber screen on a RAIN model (including inside the screen holes), helps the white surface reflect more light back to the roots of the growth, allowing for more days of attached growth to occur before it lets go.
If the focus instead is more pods (and not more filtering), then you want to leave as much growth in the scrubber as you can, for as long as you can, and clean/harvest it minimally so that the pods grow and multiply more. So multiple scrubbers are not needed. And in saltwater, if you can clean/harvest with saltwater (or just harvest in-place without removing the scrubber), then you will have the most pods possible for feeding. Pods also occur in freshwater tanks, but less so.
Here are two HOG3 units which have strings for saltwater; for freshwater you don't need the strings, and a HOG2 or 2x is fine:
