Saltcorner
By Bob Goemans
By Bob Goemans
Hi Bob Goemans!
I am Danish and new in this hobby, but have had the interest for many years. I have met people with many years of experience with saltwater aquariums and have already gained knowledge from some of the good ones. Have also enjoyed reading your articles and booklets.
Two weeks ago we receive the first live and dead sand shipment from the US in Denmark. It is very expensive, but I have decided to try it. I have been "selected" because I will start my aquarium from the ground up and maybe also because I am more serious about this hobby then the average hobbyist and want to try the plenum method in my new reef aquarium. It is a 450 gallon/1350 liter corner diamond-shaped aquarium. Because I am the first in Denmark to try this plenum method and I also want to do it in a way which will also look nice I have some questions for you. In the front where the plenum stops I have decided to mount a 5 cm (2 inches) high glass wall secured to the bottom with silicone so the plenum will fit into this area. The aragonite sand will then not enter the plenum area. I have then approximately 25 cm (10 inches) to the front glass where I would gradually (as fast as possible) decrease the sand level to 2.5 cm (1 inch). Do you think this is OK?
Another question is: Does the plenum area start at the top of the eggcrate, or is it the open area under the grid that is called the plenum? Will you clear this up for me, please?
To elevate the eggcrate from the aquarium bottom you describe the use of PVC pipe. Do you lay the PVC pipe horizontally on bottom in long lengths or do you cut the pipe into small pieces in the right height, which I guess should be between 2.5 ? 3.5 cm as you describe. This means vertically placed so it stands on the bottom. I know that holes should be drilled into the pipe.
I also plan to put 100 kg "dead sand" aragonite and 25 kg live sand in this mix, is that OK? (remember it is very expensive even in this mix, about $800, almost as it was gold!) I will buy some more if I don't reach the 10 cm (4 inches). And do you think it is the best to place the "live sand" nearest to the plenum or in a mix or nearest the bulk water?
I have in mind to wash the live sand two to three times in used aquarium water from a shop before using it. And the dead sand in RO water. Does that make sense to you?
I think you/those in the USA are a couple of years in front of Denmark when it comes to reef aquariums. Sorry to disturb you with these questions but I know if I don't ask the result would maybe not be as good as it could be. And I would like to show my friends the right way to do it!
Thanks and best regards,
Torben Høffding
Copenhagen, Denmark
Hi Torben,
Thanks for your email and many good questions. As for sand cost you could have used crushed coral and saved some money. Aragonite is recommended simply because it helps supplement system alkalinity. The most important aspect of the sand is that it be the right size sand grains. Once a system is up and running with many stony corals and coralline algae, aragonite dissolution will not keep pace with their and/or system alkalinity needs. A calcium reactor should be considered if possible. A reactor probably pays for itself in the long run and I think you'll find the system much more stable than it would have been if using separate calcium and buffer additives.
It appears you do not want to have a deep sandbed look at the front of your aquarium. By slanting the depth of the sandbed directly on the aquarium bottom from the barrier to the front of the aquarium you'll be creating an area that will not have the same microbial efficiency as the bed of sand over the plenum. Nevertheless it sounds like the majority of the aquarium bottom will be covered with the plenum and easily prevent the bulk water from becoming 'too' nutrient rich. This sloping area should be occasionally stirred to lessen anaerobic areas.
The area under the top surface of the screened plenum grid is still mostly an open space even though the grid itself is eggcrate material. Therefore everything below the top screened surface is considered a plenum. As for positioning PVC pipe, either horizontal or short vertical pieces can be used. The grid assembly simply has to be strong enough to support what will be paced upon it.
Starting the system with some live sand helps introduce bacteria and shortens the time needed for them to spread throughout the bed. Since live sand probably contains more nitrifying bacteria, therefore placing it on top helps to reduce the first ammonia the aquarium will experience. Rinsing the newly arrived live sand helps to remove any nutrients that may have accumulated from the time it was packaged. Rinsing the dead sand is always recommended as that removes a lot of the grit/powder often found in the bags.
When it comes to experience with reef aquariums, the United States has been fortunate enough to have a thriving economy and the availability of many aquarium products at reasonable prices. Otherwise, the desire to learn is worldwide. I would be very interested in your progress. Please keep me informed.
Hope this helps,
Bob
