29 bio cube flow problem?

[joe_patterson]

i have had my tank cycleing for about 1 month. live rock, live sand snails and hermits. my question is, even with a new filter cartridge the pump sump seems to run low. almost sucking air at times. currently i have moved the filter from its factory location to on top of the bio chamber. this seems to be an ok temp. fix. has anyone experienced this problem. what was the cause/fix?

 

[jmcmahon66]

I have a BC14 and had the same thing. I felt the opening between chambers 1 and 2 was too small for the water flow. I used a dremel and widened it. This allows water to bypass the filterpad, but I never used the stock pad anyway. HTH

 

[AndyNarwhal]

There are two things you want to check.
1. Make sure the tank is sitting level. If it is tilted down in front the tank will appear full (even like it's overfilled) and the pump will run dry. The tank needs to be level.
2. Biocubes are true wet/dry filters which means that as you evaporate or take water out of the tank the water level in the sump where the pump is located will drop but the tank water level will remain the same. You just need to add more water to compensate for evaporation.
If the cartridge clogs the water level in the tank will rise until it begins to go over the top of the front wall of the filter. Cutting the plastic wall between chamber 1 and 2 will not increase the flow at all. This will only allow the water to drain more easily into chamber 2 which would drop the water level in the display area of the tank. You may get some more efficient surface skimming as a result. Only the pump will determine how much flow is going through the filter. Water in= water out.

 

[jmcmahon66]

I completely disagree with you Andy. Joe_patterson posted that his pump sucks air in, indicating that chamber 3 is low in water. This was my case as well; the aquarium was full of water and chamber 3 was low ( as was chamber 2 ). To increase the water level in chambers 2 and 3 I needed to cut the opening from chamber 1 to chamber 2. This lowered the level in chamber 1, and increased the level in chambers 2 and 3 thus making the pump suck less air. This only occured after I changed my stock pump to a MJ 1200. The water level in the tank was close to overflowing while the pump chamber was almost dry. I hope this clears up my response to the original poster.

 

[AndyNarwhal]

I have no doubt that your solution worked jcmcmahon. But it was not the simplest solution. The wall between chambers 1 and 2 is the lip of the overflow box. Your solution lowers the water level in the tank and chamber 1 by increasing the opening of the overflow horizontally. It does not increase FLOW. That is determined solely by your pump. It does lower the water LEVEL.

Making sure the tank is level increases the opening of the overflow box vertically. It requires no cutting and should be done as a safety factor anyways.
If you look at your Biocube you will notice that the top of the front wall of the filter box is 0.3" below the bottom of the lip that goes around the frame of the tank. If the water line is touching the lip at the front of the tank and not flowing over the top of the filter box in the back at the same time then the tank is not level by at least 0.3". This has a dramatic effect on the filter. If you visualize the tank like a lever with the center of the tank being the fulcrum you can see what I mean. When you tilt the tank forward the back of the tank raises. This raises the lip of the overflow box which means that in order for the water to move at the same rate over the lip as it did when the tank was level the water level of the main tank and chamber 1 has to rise. At the same time the front of the tank moves lower causing the water level to rise at the front possibly to overflowing. The filter box was made intentionally lower than the tank frame to compensate for the fact that if someone upgraded the pump, had a clogged cartridge, an algae covered strainer or any other factor that would increase the water level in the main tank or chamber 1 the water would flow over the top of the filter wall and back in directly to chambers 2 and 3 to maintain equilibrium. Remember water in = water out.
If Joe is using the stock pump or even a Maxijet 1200 on a 29 solving Joe's problem is as simple as just putting a level to it and shimming under the front as necessary.

Andy Hudson
Product Validation Technician
Central Aquatics (Developers and Manufacturers of the BioCube)