jcastell said:
my problem with wanting well mixed flows is that most canister filters don't accommodate it according to their usage literature. And Eheim 2217 is said to be used for tanks up to 600 litres!! With our ways of thinking this is way too optimistic.
Yes, Eheim are known for their optimistic flow ratings. In non-planted, low stocking level tanks this doesn't matter, especially when using high surface area media such as their generally overpriced sintered glass media (or competitors equivalent.) While detritus does build up, Eheim and others assume this will be taken care of via water change. As these generic tanks are also typically low light there is much more margin for error. Manufacturer's tank capacity filter ratings are therefore based solely on the ammonia pull-down ability to levels which would show zero on a consistent basis on an ammonia test kit (assuming a fully cycled tank).
jcastell said:
I've looked at Amano's filters, he uses a very strong pump that has a much higher head than Eheim or any other manufacturer uses, this means as the filter clogs it doesn't lose that much flow rate.
What I'm trying to get at is that flow rate for it's own sake can be achieved with loads of in tank flow pumps that do nothing but encourage water flow. But where does that leave the canister filters used. For the sake of argument you could have just one Eheim 2217 and loads of flow pumps in the aquarium to achieve your objective, but that would not be the way I would want to go about things.
Yes, many folks find that simply adding Koralias or other pumps will add flow and this, if distributed correctly will definitely achieve the objective of addressing the boundary layer issues, enabling better penetration of nutrients/CO2.
Filtration and Flow/Distribution are separate entities. Flow is as important as Filtration because it feeds the plants, so there is
value in adding more pumping, but there is an aesthetic penalty. After all, the fashionable trend is to remove equipment from the tank for a more natural look. Using a filter(s) that satisfy/exceed the 10X rule kills two birds with one stone and satisfies the aesthetic imperative.
jcastell said:
In the interests of this thread please answer the following:
1) Is the biological load just as much a function of the plants kept as it is of the fish in the aquarium too? Dead plants produce ammonia, so you want it dealt with biologically, having good mixing will allow for the dilution effect but this also needs to be backed up with sufficient biological filtration and sufficient contact time with the biological filtration. In the other thread mentioning about canister filters you said the throughput was a problem. I stated it was not, but another thought also occurred to me: it makes no sense to have a 2217 canister pumping 2000 litres per hour or more because the contact time with the biological colony is decreased. The larger the canister the higher the flow rate we can put through it, and Amano seems to use quite conservative flow rates for his canister filters given their size and it strikes me that he wants to increase contact time with the biological colony when the water gets through it.
Plants add to the bio-load, not just because of dead leaves, but because of the high metabolic rate induced by the high lighting and massive carbon (and other nutrient) consumption. This results in ejection of carbohydrates, lipids and proteins which incidentally, feeds the critters in the bio-film/filter. I'm guessing that this actually speeds the metabolic rate of the microbes which affects the ammonia production rate and levels. But there is plenty of space on the bio-media and the oxygenation which occurs as a direct result of plant photosynthesis also finds it's way to these critters thereby enhancing their populations. As long as there is plenty of bio-media and microbial population one need not worry too much about contact time of the water with an individual bacterium. This has never been an issue with high throughput filtration.
jcastell said:
2) what happens to the detritus that sinks and ends up in the gravel? Do we still have to clean it out or will it rot and break down of its own accord? Apart from going to extremes we are always going to get some that will end up in the gravel (depends on fish loads of course!). Is this one of the reasons why people get blue green algae in the front glass since it's been triggered by this?
Detritus not picked up by the filter rots in the sediment. The combination of this rotting and any external lighting does contrbute to the BGA seen at the sediment line. Running a length of black electrical tape along this line will cut the light and reduce the amount of BGA formation. Good flow distribution to the bottom also minimizes this problem.
The rotting is also precisely why it's not a good idea, in a high light tank, to disturb the sediment without then doing a water change to dilute the ammonia that has been kicked up. The result is often algal blooms. Those with a fully carpeted bottoms have little choice though, except when changing out carpet sections or re-scaping. This isn't too big of a deal as the ammonia in the sediment feeds the carpet plant roots.
Cheers,
) Nice article Darrel. Excellent data for any fish and any tank, really.
