Based on this score, the best time of year to visit Nakuru for hot-weather activities is from mid January to mid March, with a peak score in the third week of February.
Step 1 - Rinsing. Especially for larger neoprene-based items, you should be rinsing for at least three or four minutes straight after every use. Try to rinse using clean, fresh water applied in a directed spray. A shower head with a removable handle will work for smaller items, so you can direct the spray in the tub.
The stains are a combination sweat and the chemicals in the deodorant. Though the shirt is white, I wouldn't use bleach as this can make such stains worse (actually more yellow.) You can try soaking it in an enzyme pre-soak product such as Oxyclean, you can also rub the stains with white vinegar.