To Flush or not to Flush?

The ppm in my ebb and flow keeps going up.
should i flush with clearex or just plain water?

E&F
Rockwool/hydroton
4 weeks into flower
1000 hps
ph 6.4
ppm 1800 +


Thanks

If the water going in is ok within ppm standard, then yes final phase works good on cleaning all grit and grime that you dont see and will lower numbers in return for you