sizing and dual filters
Those "sizing" guidlines are for tanks with no decoration, and no dirt in the filter. If you are depending on one filter, you need to go much larger to be safe. The second filter is moslty for circulation and some emergency backup.
If the main filter failed, the HOT would buy you some time to get it replaced. Once you knew you had lost 80% of your filtration, you'd be doing massive water changes and no feeding to keep up with the load. But, you would not expect to come home and find the tank dead which might be the case if you had only one filter. You would have some help from the HOT.
The other answer is to get two filters sized for 90 gallons each, you have 2x sizing so are adequately covered, both use the same parts so less stuff to keep on hand, and flow circulation can be matched through the tank. Not the cheapest answer, but if money is not the issue, that is the best answer.
Realize that if any filter goes down, the remaining filter cannot instantly support the bioload, there is still a shock to the system. A HOT could only do so much, even if fully cycled and full of bacteria. Even a pair of 90 gallon filters will be shocked when one goes down suddenly, though recovery may be more rapid in that case as the large filter takes over.
Roan Art said:
Those "sizing" guidlines are for tanks with no decoration, and no dirt in the filter. If you are depending on one filter, you need to go much larger to be safe. The second filter is moslty for circulation and some emergency backup.
If the main filter failed, the HOT would buy you some time to get it replaced. Once you knew you had lost 80% of your filtration, you'd be doing massive water changes and no feeding to keep up with the load. But, you would not expect to come home and find the tank dead which might be the case if you had only one filter. You would have some help from the HOT.
The other answer is to get two filters sized for 90 gallons each, you have 2x sizing so are adequately covered, both use the same parts so less stuff to keep on hand, and flow circulation can be matched through the tank. Not the cheapest answer, but if money is not the issue, that is the best answer.
Realize that if any filter goes down, the remaining filter cannot instantly support the bioload, there is still a shock to the system. A HOT could only do so much, even if fully cycled and full of bacteria. Even a pair of 90 gallon filters will be shocked when one goes down suddenly, though recovery may be more rapid in that case as the large filter takes over.
