Thanks for the links. I made my way through the first one so far and am tackling the rest as as I have time.
:read: :thumbup: :beer:
However, I don't really see anything in there on how an ATS which is a remote turf algae grower to export nutrients would be detrimental in a reef system. Especially in a system running multiple levels of filtration (something I do with a big skimmer, UV, carbon, phosguard, purigen).
Think about that list for a bit. Save for the skimmer, the chemical media binds organics. They are "sinks" and when they fill out, they stop binding correct? Now, there is another major sink in out tank. Calcium Carbonate. Yes, our sand and rock are also binding phosphate (when hair algae on rock can persist even in a clean tank... for a while). Few talk about how good an agent calcium based media is for binding phosphate. Calcium is used for binding phosphates in dialysis treatments. So in our tanks, we create multiple phosphate sinks. Rock, sand, algae, phosguard/GFO, and etc... The trick is that the more we use, the more difficulty we have at tracking where it is sinking and how full each "sink" becomes. Think of it as a port-o-john with 4 "dug holes" and you do not know were the poo is going. If one fills up, the other take in the extra... but they are also filling up until you have four nasty poo-filled holes and no-where to go. As a result, that is why many folks (but Geoff in particular) say that GFO, algae, and other methods are masking the bigger problem. Eutrophication. The system is gaining mass (phosphate being the real enemy) and we are spending a lot to "cover it up" in the system. In the end, algae out of all the phosphate consumers is actually one of the lest effective methods as GFO, calcium, etc are often much better at getting and binding it first... so algae get the scraps.
Think of it like the family dog during the holidays getting the scraps of the turkey. If you are feeding the dog enough for it to reproduce enough to have a steady supply of puppies, that is a lot of turkey and gravy making into the dog bowl. But algae for nutrient control is the same way. How many turkey scraps do you need for dog population to grow to remove the puppies from the house to "clean up the leftover turkeys" from the house. Keep in mind of how much poo those puppies make as well.Same concept. You can not use an growing organism population to control the nutrients from which it is dependent upon. Either it will reach stasis and neither grow of collapse or it will die. You can use humans to "export" oxygen by removing babies. Either there will be ample O2 for us to consume and procreate or we run out and die. Algae is no different but it is smart enough to start culling itself before it runs out.
What the first link seems to indicate to me is that algae overgrowth is detrimental and that paper seems to speak to the relationship between herbivores and algae; how that can impact reef health in general. I don't see how that's really applicable in the case we're discussing since macro algae in this case will be constantly removed as part of nutrient export.
Herbivores control the algae biomass so that the tides can come in a "sweep" away the organic material into the abyssal plain, otherwise a lot of algae is quite good at trapping organic material nearby. Same with out tanks. A good modest collecting of snails is great at turning small amount of algae into poo so that we can siphon it out.
For algae to grow in biomass, there must be ample nutrients. Cultivating algae means you must have these nutrients in high enough concentrations... it does not control nutrients, nutrients controls algae.
This discussion's timing is pretty funny right now though. My skimmer has decided to micro-bubble like crazy this afternoon. Skimmers in general have been the biggest pain in the butt as far as reef equipment go for me. I'm not going to stop using one in my main system but man do they require a lot of maintenance and trouble shooting.
Skimmers are not necessary but they do lend a specific cost/benefit effect for larger tanks. A skimmer (which is the only piece of equipment that actively removes organics) make it easier to reach a specified organic level combined with a water change. Thus, skimmers are to make water changes more effective at achieving an trophic level. Skimmerless is acceptable but increase WC are required and it might be more frequent. Thus skimmers "pay back" their initial and operating cost over time in water change volumes. Big tanks can take advantage of this better than small. Plus skimmer have some other fringe benefits such as aeration and pH stabilization. Algae unfortunately, can not provide these benefits.
Some skimmers are good, others are evil. You might want to consider the time/effort/cost for running a skimmer vs additional water changes.