THIS DISCUSSION IS BY A RECREATIONAL DIVER FOR RECREATIONAL DIVING WITHIN RECREATIONAL LIMITS
To be able to calculate and setup a Balanced Rig you are going to need to have done proper weighting calculations and weight checks so you know how much weight you need to compensate for the buoyancy of EVERYTHING other than your full tank. Go do that now or this won't be useful.
At a fundamental level, the EXTRA amount of weight (beyond what you calculated above) you need as a recreational diver is ONLY the weight of the gas you will consume on the dive. That's literally it. Plain and simple.
If you carry only that amount of weight, you are...by definition...diving a "Balanced Rig" and you might not even know it. The disagreement that shows up when discussing Balanced Rigs is the amount of ditchable weights you should or should not carry. I don't think it is as simple as black and white for recreational divers on a limited budget and thus cannot change out various pieces of equipment to match the optimal weight placement...so let's dive into both sides of the argument. To me...it's a risk calculation disagreement which means only you will be able to decide which one you agree with.
When using a single AL80 tank, typical of a recreational dive, and assuming you are properly weighted for the gear you are using you are ONLY compensating for ~5 lb of INCREASED buoyancy at the end of the dive compared to when you started your dive. And any reasonable swimmer will be able to "swim up" 5lbs of weight if the BCD fails.
You'll hear all sorts of various justifications for ditchable or not ditchable and it all distills down to either....
- Why have the option to accidently ditch the weight if I will "never" need to?
- If I have a way to ditch the weight, why not give myself that option?
Having experienced accidental ditch on my 2nd open water certification dive and having never experienced a BCD failure in ~100 dives...I know which one is more likely to occur to me. However....
...having determined for myself that I don't NEED ditchable weights that doesn't mean I don't HAVE ditchable weight pockets on my belt. Purists of the "Balanced Rig" concept will argue that my setup is not "balanced" because I have not opted to change my tank configuration or my BPW configuration to eliminate the belt pockets. I don't have the kind of money to have multiple different configurations for every situation to be "perfect" to the concept. So I do the best I can.
My BPW (xDeep Zen) has ditchable weight pockets on the belt...but I don't use them for ditchable reason...I use them because that is how the xDeep Zen was designed to carry weights that exceeds the capacity of the tank band pockets. I only use them when I need to carry more than 8lb of weight (2 x 4lb tank bands) notably only when wearing my DrySuit or 7mm wetsuit, but I do not touch them once they are locked in.