what a lot of worry about nothing. if you evap 5L a day which sounds low, it would take a while(read weeks)to lower your sump enough to harm your pump.UNLESS yr sump is designed with a flaw :-?
I use the HPM ones but my M/H's are only 150w & they work great.
On the Taka tank I run HPM but 250w M/H & same prob as you
when halides start up they draw huge current, jump in here Layton
Fay, I have used Zeovit for 6-7 months with no bad effect my Xenia is growing so fast I'm selling it as quick as i can frag it, Just follow the programn & all will be fine . Steve