Hello. We thank you for your inquiry. This model has a base diameter of 9.25". We hope this helps. Your biOrb Specialist, Mary

The number of bettas that can be kept together in the same aquarium depends on the gender of the betta. Only one male can be kept in an aquarium, as males will fight with one another (hence their common name, Siamese fighting fish). In the wild, one would retreat. But that isn't possible in an aquarium; fighting continues, to the death of one or both.

The biOrb does not come with a heater. A heater will need to be purchased separately. We recommend the biOrb Heater Pack for all of the biOrb aquariums. The biOrb Heater Pack comes with a 50 watt glass heater, acrylic stand, thermometer, and set of instructions. We hope this helps! Best Regards, Your biOrb Aquatic Specialist, Jennifer.

I have already bought AND LOVE the 8 gallon bioOrb. I have a very happy male Betta fish and lots of real plants in it and everyone is quite happy and healthy! I don't believe in plastic plants or decorations in my tanks but that is just the way I like it. I will soon get the 16 gallon one. I would really like the largest one but at almost $400 I don't think so...

I can answer that!!!! YES YES YES

I have an 8 gallon. with live rock and saltwater. No trouble with mine as long as you don't over stock, Seriously like maybe a shrimp and a small clown fish. and keep the water clean. Use buffer. etc. Adding live rock helps quite a bit.

I would recommend the Maintaining this tank like any other small aquarium. You'll want to do weekly water changes of maybe 10% or bi-weekly of 20 to 25% of total water volume. Don't use tap water that has been "Classicly Rested" unless you know for sure that your Water Municipality doesn't use Chloramine, Regular chlorine will evaporate but Chloramine doesn't work that way. It still needs to be neutralized with a quality water conditioner. You can use a small water vacuum to suck up the gunk that builds up in the substrate when you are doing your water changes. Use a gentle scruber made for acrylic tanks to wipe off any algae that may form on the inside of the bowl before you do the water change so a lot of the floating algae you scrub off can be removed by your water change as well. Other than that I wouldn't recommend any other "Cleaning" methods. It's a fish tank, not a countertop. You are not going to want to disinfect it or use any kind of chemicals around it as you could hurt the living inhabitants. It looks like this tank uses an under gravel filtration system. Now and then if you don't see any movement through the gravel - you may want to take the inhabitants out of the tank and put them in another container like a clean bucket (that hasn't been used with any chemicals) You can then take everything out of the tank and wash the gravel with tank water. Don't use normal tap water to wash the gravel as you'll kill all the beneficial bacteria that builds up in the gravel. This can cause a spike in ammonia or nitrites or other unpleasant things to happen. If your being careful with your water changes and vacuming the gravel each time you change the water you may never have to do this.