Originally Posted by
zhuls1
I'm going to build a huge sump for my next aquarium with the equivalent of around 50 baskets or more and a small algae scrubber.
That is a whole lot of BCB's, how big of an aquarium are you thinking about getting? With that many baskets you must be planning on a lot more discus. Personally, with that many baskets I wouldn't bother with an algae scrubber. their are many reasons as to why we change the water. one reason is to remove toxins, or undesirable chemicals. This includes Nitrates, phosphates, dissolved organics, heavy metals, proteins from the water column etc. The BCB takes care of both nitrates and phosphates. If you want the ultimate filtration system, you will want something to remove disolved organcis, proteins and heavy metals. Fortunately, proteins have a tendency to float so using a filter sock or filter floss to polish the water after the overflow will suffice for its removal. As for dissolved organics and heavy metals, carbon should be able to remove it. if you are planning on going little to no waterchanges, I think you should definitely chuck some carbon into the mix. Another reason we do waterchanges is to keep parameters stable. Typically, the nitrifying bacteria makes the water more acidic, so the longer you go without a waterchange, the lower you PH would get. I don't know what effect the BCB's have on PH but I dont think it alters it as much as typical nitrifying bacteria. I would suggest doing a waterchange whenever you can measure a change in PH. Some good quality carbons and other chemical filter medias can help to maintain a stable PH. If you really wanted too you could even go to the extent of using a reactor to maintain a stable PH to really push the limits of no water changes, but I don't think its necessary as you would have to adjust it precisely to your tank. A chemical media such as carbon IMO is a much better option for maintaining a stable PH. Finally, we do waterchanges to add minerals back to the water column. This will really depend on your setup, plants obtain a considerable portion of their minerals through the water. Where as fish, for the most part, get their minerals from their food. if you only have fish and no plants, adding minerals to the tank is less important as fish do not use a lot of minerals from the water column itself. A final reason as to why we do waterchanges, is to remove organics and unwanted organisms from the aquarium. This includes, decaying food, parasites, dying plants etc. another way we can remove organics from the watercolumn with out doing waterchanges is by doing frequent filter sock replacement. Also, I suggest having a particularly high flow rate to prevent dead spots where debris will settle. With good flow within your aqaurium, you can prevent nearly all debris from settling at the bottom of the tank in the first place. Another method of removing proteins and organics from the water column is with a protein skimmer. I have heard of a few people who used protein skimmers on freshwater aquariums with good results. How they do it is by attaching a large air pump to the protein skimmer. This allows it to function in freshwater. Albeit, It is still not as efficient as it would be in saltwater, it does work. Personally, I would look at using a protein skimmer instead of an algae scrubber. Or if you really wanted to you could use both. The benefit of a protein skimmer is it removes waste before it gets a chance to break down into nitrates and phosphates to begin with.