Jetted Tub Jet Cleaning Tool Kit & Specialized Dissolving Solution

The user is struggling with deeply embedded 'disgusting orange ish brownish sludge chunks' in old jetted tub jets, which common cleaners fail to remove. A specific cleaning kit could include flexible, durable aquarium-style brushes (as suggested in comments) designed to reach deep into jets, paired with a powerful, specialized dissolving agent formulated to break down old mineral deposits and organic sludge without damaging the tub materials. This would address the frustration of impossible-to-reach grime.