I would like to offer some comments on a couple of issues in the last few posts. First up, daizeUK is quite correct that it takes plants a couple weeks to adjust to changes in lighting, fertilization, etc. We had a few issues here so there was more than one suggested change, because we are (hopefully) establishing a more realistic balance level. But this needs a couple weeks, then it can be tweaked depending upon the response of the plants and algae, but the tweaking will probably be one thing at a time at that point. Primarily, you want to see algae not increasing further beyond where it is now, but you also don't want to see a decline in the plants. We (you and other members) can discuss issues at that time.
Second point is on the bubbles and surface disturbance. This is a relatively new idea that I first came across two or three years back. Prior, any reliable plant source (Hiscock, Walstad, etc) advised against excessive water disturbance at the surface (from filters) or via bubblers. When I read Rhonda Wilson's article in TFH in which she went counter to this, I questioned it on plant forums with people like Tom Barr and Amanda Wenger. In the final analysis, no one has any documented evidence that one can increase CO2 by increasing water disturbance. However, some disturbance seems helpful, provided it is not taken to excess.
Which brings me to the CO2 in aquaria. The majority of natural CO2 occurs from the breakdown of organics in the substrate. The CO2 added from respiration of certain bacteria, all fish and all plants [yes, plants also respire the same as fish 24/7] is minimal by comparison, or should be. This is why the substrate is normally not overly-cleaned; you want a build-up of organics as that is your prime source of CO2. But like everything, this can be taken overboard. It too is part of this balance I keep referring to, involving the light intensity, light duration and nutrients.
During daylight, meaning when the tank light is on with the purpose of driving photosynthesis, and assuming that all required nutrients are available to the plants, they will produce oxygen and take up CO2, and much more than occurs via respiration of fish and plants (which is continuing in the plants) and usually significantly more than what is occurring during daylight from the breakdown of organics. In natural or low-tech method planted tanks, where natural CO2 is the only CO2 available, the CO2 can be exhausted after a few hours. The species and numbers of plants, the available nutrients, and the light intensity all factor into this equation. Plant photosynthesis will slow and may even stop, and at this point one usually ends the duration aspect of the light, again because it will only serve to promote algae from this point on.
During darkness, meaning when the tank light is not on, and the room is relatively dark to completely dark, the CO2 rebuilds from respiration and organic breakdown. Some will advocate adding water disturbance during darkness, thinking that CO2 will increase to the extent that Oxygen becomes inadequate for the fish, but this is highly unlikely unless the tank is overstocked. Obviously, CO2 would be driven off by this additional disturbance, otherwise there would be no possibility that Oxygen could enter the water. No one argues this, so the conclusion clearly is that excessive disturbance of the water/air relation is going to be detrimental because valuable CO2 is being lost, and there will be even less during the daylight.
So, to sum up my thinking on this matter of water disturbance, I would suggest it not be excessive. I have surface disturbance in my tanks, via the filters, and I would consider it relatively substantial but not excessive. I do not use bubbling devices, aside from the sponge filters in smaller tanks.
On a related point, the liquid CO2. Obviously many people use these products--and I am referring here to those products made from glutaraldehyde such as Seachem's Excel and API's CO2 Booster--and the fish are not dying. But that does not mean it is wise to use them. I cannot understand anyone thinking that adding such a toxic chemical to an aquarium is safe. As I mentioned previously, even when used according to the manufacturer's directions, some plants (Vallisneria for one) usually die outright. If overdosed, other plants can deteriorate, and both fish and bacteria can be killed with enough of it. This chemical is used in hospitals to disinfect surgical instruments, and in ship's ballasts to kill bacteria when the ship moves from one ocean to another. Obviously the chemical is toxic. Some people won't use conditioners that have aloe vera in them (and I agree), yet they will use Excel and think nothing of doing so. There is a real risk; any and all substances added to the water in an aquarium enters into the fish across the gills or by osmosis through every cell on the body. The fish is going to have to deal with this; and if the product does cause issues for sensitive or spawning fish, that is a sure sign that it is affecting the fish to some degree whether it is seen in all of them or not. I do not see any logic in risking the fish when it is not necessary to begin with, as the natural CO2 can be adequate. If high-requiring plants are intended, then diffused CO2 will likely be necessary. But it is possible to have a lush planted tank following the natural or low-tech approach if you select the plant species with this in mind.
Last issue is the blue night light. This does affect plants and fish, so it must not be on all night. But during the evening for example should not pose problems, provided the aquarium receives several hours of absolute and complete darkness. This is essential for the circadian rhythm in fish, and plants have much the same thing.
Byron.
/www.caiber.com/info/UCARCIDE%20CATALOGO.pdf
