Posted: Thu Sep 06, 2018 11:24 am Re: Turtle Tank dimensions
How long you had the turtles or did you raise them from babies ? Adopted or rescue ? What is the sex of the 20 year old being about 6" ? If male may be full grown but if female can reach 12" needing a much larger tank "alone". Other two may not be sexual mature yet to tell sex to get a final home yet. All three in a 75 gallon to me will be a very large bio load on any filter. Resulting in lots more maintenance and more often water changes. You may know how we all just love doing maintenance. Haha ! That's a confined space for three even if filled full with an "ATBA". Upfront if 20yr old a male 6" the 75 gallon would be great for him alone . Then another tank for the two smaller ones being about the same size. They may get along for awhile until sexual maturity. Turtles are territorial , aggression will happen in small tanks and yes to me 75 is small for three turtles one being an adult. You may get lucky with the smaller ones about same size in another tank , then sex will matter down the road , if separation needed for them also. Normally 10 gallons of water for every inch of shell works. This is not just for more swimming room but helps a lot to control the waters parameters. You don't want small turtles in with the larger 6" , things will happen. You can not watch them 24/7 ! The personality's , aggression , sex all matter to have a happy setup. Yes some people do have three turtles in one "large" glass or stock tank , lots of factors must come together for it to work. Also keep in mind when all are adults in size , that's going to be large tanks and maybe two or three depending on the separations needed.