24 ppm FC with 90 ppm CYA (at pH 6.8) is technically equivalent to 0.5 ppm FC with no CYA (at pH 7.5) so isn't as strong as most indoor pools. It's safe to swim in in terms of the chlorine level as long as you don't drink lots of pool water (the FC is the relevant number in that case). However, the low pH is not good and since we don't know how low it actually is, I wouldn't swim in it until it gets to at least 7.0 (even then this will sting the eyes).

Richard