If what is in your tank is clogging your syphon, then its doubly sure going to clog any battery powered gravel vac on the market.
If clogging is truely an issue, it isn't impossible to DIY a vac that will work for you. Instead of running tube straight into your sink/bucket, get a large widemouth jar with a solid lid that will give a tight seal. Drill two holes in the lid of a smaller diameter than your tubing and silicone the lid around where the two tubes enter. You basically make a knockout pot that will collect the detritus before its pulled into your sink.