Hi all,
cheers Darrel
This is because of the large gas exchange surface, and a problem when you add CO2, but an advantage when you don't. I think Tom got around it by sealing his sump <http://www.ukaps.org/forum/threads/co2-ph-level-in-planted-tank.26559/page-2>.Major issue with sumps and planted tanks and CO2 is severe CO2 loss
I've never thought of it like that, but that would actually be an advantage. I've strongly recommended reversed lighting sumps in the past for keepers of fish with a high oxygen requirement and I still think that a wet and dry combined with reversed lighting in a planted sump is the "gold standard" for filtration.Canister filters are far inferior IMO, you can achieve a lot with a custom sump, and they are just as relevant in a planted tank as a marine one..... I'm also surprised that no one seems to have experimented with reverse lighting setups using a sump and lots of fast growing plants. This way you can have a constant supply of CO2 when needed for good growth from the respiring plants below.
From <http://plecoplanet.com/?page_id=829>.....Aquatic plants will be net contributors of oxygenation when they are photosynthesising, but when they are not they will be part of the bio-load. You could take advantage of 24 hour photosynthesis by using a sump refugium with reversed lighting regimes (dark in the tank, light in the refugium).
cheers Darrel