A little info first!
Why bio balls? Let me start by saying this is just my 2 cents. I don't think bio balls are better than other types of media. Bio bale, rock, beads, mats, there all good. Bio balls are just very popular and pretty cheap so, I will focus on them. The main point of this section is to provide info about the use of mainly bio balls but can help with other media.
If you are running a bare tank and are keeping a lot of fish you are going to need a lot of biological filtration. You are going to need plenty of surface area for nitrifying bacteria (Nitrosomonas & Nitrobacter) to live on. Bio balls provide the neccasary surface to support enough bacteria to convert all the ammonium/ammonia generated in the tank. This makes up for the lack of surface area in a tank especially a bare tank. The bio balls also provide an oxygen rich enviroment needed for the bacteria. They are suspended above the water and have water flowing and driping over them which provides adequate oxygen levels. This is why they are called wet/dry systems. Also arowana or discus owners should keep in mind that pH levels affect the the ability of the bacteria to convert ammonia. At low pH levels the amount of ammonia converted reduces. For example lets say at a pH of 7.0 the nitrification process is at 95%. If the pH drops to 6.7 then nitrification may only be 70%. This continues to get lower until at a pH of 6.0 it is 0%. So in tanks with fish like arowana & discus that prefer slightly acidic water like a pH of 6.8 you really have to make sure you have the ability to support plenty of bacteria.
GET THE MOST OUT OF YOUR BIO BALLS!
Here are some ways I have found to get the most out of bio balls. First, make sure most of your media is out of the water. The last bit thats under water should be covered in bubbles, but I'll explain more on this later. If they are submerged they don't get the oxygen they need. Second, try to get the most surface area of media per the volume of space you have. There are brands like pentair that have more surface area per ball than others. Some of the really small balls like currentUSA nanos dont have as much surface per ball as others. However, what you are looking for and this applies to any bio media is surface area / per volume. (Bio bale is actually better in this regard). As for bio balls I will compare 1" , 1.25", and 1.5" diameter balls of the same brand. OK Lets say your wet/dry filter has a 10" x 10" x 10" box or 1000 cubic inches to hold your bio balls. You could approx. use:
- 1000 x 1" balls = 95.56 SQ. FT. of surface area
- 800 x 1.25"balls = 77.64 SQ. FT. of surface area
- 667 x 1.5" balls = 59.73 SQ. FT. of surface area
So you can see from above that by using 1" diameter balls in a given volume you can get more surface area. Finally, make sure all of your balls are bieng used or have water flowing over them. This can be done with a spray bar, drip plate, and or anything else you can come up with. I prefer to use drip plates. Spray bars can clog easy and also restrict flow in the plumbing on a gravity drained system. Also, I have filter padding above the bio balls to keep large waste particles from bieng trapped in them. I get alot more splashing with the pad removed. However, the fast flow and extra splashing doesn't really improve anything and there is less noise with the padding in place. If you use padding it must be below the drip plate. Look at these pictures to see how much improvement a drip plate makes. I wish I had a video clip of this, you would really see the difference!
No drip plate
Notice the water only flows through the center
Not very much splashing on the sides, its pretty much just flowing straight through.
These are the submerged balls notice there are only a few bubbles in the center of the egg crate. All the submerged balls here are wasted.
With the drip plate
Much better! The water is being spread out over all of the media.
Now the sides are wet from splashing.
Click and enlarge this picture. Look at all those bubbles! Now even the submerged balls are getting used.
Here is how I made my drip plates. I have two bio ball sections, but I will just show how to make one. First, I used 1/8" acrylic and cut the plate to the exact size of my bio ball section. Second, I marked a one inch grid on the plate. I started the lines a 1/2" from the center of the plate which left 1/2" on the edges. On my plate this makes ten holes per side and a total of one hundred holes. Next, I pre-drilled all the holes with a 1/8" drill bit. Then starting from the outside perimeter I drlled the first set of holes with a 3/8" bit. Then the next two rows with a 5/16" drill it. Then the last two center rows with a 1/4" drill bit. Making the holes smaller in the center and bigger has they go out. Enlarge the picture to get a better idea.
Then remove the paper. You may have to experiment and vary the amount and size of your holes depending on the size of your plate and how much flow you are running.
Then put it in your box and your done!
Hopefully some of this info helps you. If it does or you have any questions fill free to email me!