Hey Drewski and welcome.
The first thing we would need to know in order to help you, is the reading of your source water?
What is the alkalinity, calcium hardness, pH and TDS (total dissolved solids)?
TDS is the measurement that will determine when and how often you will need to drain your water. When TDS reaches 1500 ppm, your water is saturated with oils, particles, sweat, chemicals, etc. Once it reaches this point, the water is saturated and can no longer "hold" anything else. Your chlorine will be useless even if you have a decent reading because it can't get to where it needs to because of the saturation point of your water.
Many will determine their life of the water by clarity. I've said it before here... battery acid is clear!
Water being balanced (in your opinion and depending on what you're testing for) isn't always safe, sanitized water.
Do you have a local dealer that offers water testing and analysis? It should be easy take your water and balance it in first day or two. Again, we would need he readings I asked for above to give any so of recommendations.
A "party tub" can go south on ya pretty quick if you're not being pro active. Can you tell me what you mean by "slow absorption chlorine"? Is this in a puck form? Shocking should be done weekly though the addition of dichlor maybe be needed in smaller doses more often if more heavily used. Shocking can be a term that many don't truly understand. Just because dichlor is added, doesn't mean you have "shocked" your water.
Shocking is taking that chlorine to the 8-10 ppm range and superchlorinating that water. Run for 15-20 minutes with the cover off to help oxidize out.
If you ever decide to leave your water in the tub for two years again, don't invite me over OK?
Balance your water initially, maintain a 1-3 ppm chlorine and shock weekly. You can add a clarifier weekly along with a stain & scale product as well. You should also clean your filters monthly. Please don't tell me you let them go for 2 years as well?
Anyway, let me know the readings when you have them and we'll go from there.
Steve