Water Change / Vacuum Gravel

For those of you that uses gravel or some kind of substrate; and do water change once or twice a week, do you have to vacuum every time?
If you do, what happens when you go on vacation and cant vacuum or do WC in 1-2 weeks?

I have a 65g tank, with a Marineland 360 and Fluval FX4 canister filters. I think my filters are pretty good for the size of the tank but I'm new to Discus and I'm not sure how hardy these fishes are. With my previous 2 Angel Fish and 6 Glofish, I have about 2-3 weeks to get my Nitrate to reach about 40-80ppm and Ammonia to about 1ppm. I got gave away my Glofish and added 4 Discuses. Not sure how that would stack up.

How thick is the substate? When you are on vacation you will not be feeding so you won't have to clean it. The thicker the substrate the more you'll need to clean it. Try keeping the nitrates 5 ppm and if you have plants and nitrates are being used by plants you'll still have to do WC's because of all the other stuff in the water that filters don't remove. It also depends on how much food is fed. It's a good hiding place for anearobic bacteria and other pathogens. Substrate can be done with young discus
but a lot more has to go into maintenance.

Your fish will not do well if you have 40-80ppm nitrates. I have a bb tank and I clean the floor every two days if not daily. As for vacations, I stop feeding one week before I leave and I do 75% to 100% water change the day before leaving. I also top off the ATO and I reduce the lights to avoid too much evap.

I had one scenario where my sump didn't have sufficient water to keep the pump going. I have my heaters and air stone in the sump so imagine the damage that I could have done. Luckily it must have stopped working the day I got back because the tank was still at 82 degrees.