Is there a specific Gauge I need for a vacuum pump?

You don't need a vacuum gauge at all, exept for wet layup vacuum bagging. It can be handy, but it is usually not necessary. If you want to get one, the only thing you want to look for is how you install it in your setup. There are gauges with the thread on the back and others with the thread on the under side.
Or there are digital ones, but those are a completely different story.

If you are doing infusion or resin degassing, most infusion catch pots and degassing chambers have a gauge built in or attached to them so you won't often need another one. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Okay and thanks for the info...

Vacuum gauge are a must. Especially if you are doing infusion. I highly recommend the GDH200-14. This is a digital absolute pressure gauge. For infusion you can connect it to your resin inlet to get a reading of your part vacuum and leak rate.

For infusion you should definitely have a gauge - and a digital one is totally worth it if you are doing this professionally or have expensive materials under your bag.  I have one like the GDH200-14 Hojo recommends and it is awesome!  You just get much better visibility on the process with a digital gauge.

For bagged wet layup it is nice but a cheap one will be plenty - you really just need to be sure you're not pulling too much vacuum!  Having a dial gauge on a pressure pot is nice but it doesn't need to be fancy.

Remember that if your gauge is plumbed up next to the pump it will be telling a different story than if it is connected independently to the bag through a separate penetration!

A digital vacuum gauge is a must if you want aa perfect infusion. The analog ones coming with catch pots are best case a good guess. Also measuring the vacuum at the catch pot does not tell you anything. The vacuum should be measure prior infusion at the farest point from the vacuum pump, and thats the resin inlet. The Vacuum gauge should be connected to the resin inlet so you defenitly measure the pressure in the part. Also the gauge needs to be a absolute pressure gauge like the Greisinger GDH 200-14 or the Vac Checker from us.
https://www.dd-compound.com/vac-checker/
The gauges at the catch pots measure the vacuum of the pump and are also affected by possible leaks of the catch pot. Thats also the reason why a droptest doesn't tell you anything.
The pressure drop should be max 1mbar/min  and that can't be measured with a analoge  gauge.

Horses for courses Dominik. I love my GDH-200, it saves me LOADS of time. But I certainly wouldn't say it is a must for a non-production environment. Realistically, if you have the time to leave a part clamped off for 4-5 hours, then a digital gauge isn't going to tell you anything extra. If you haven't got time to wait that long, then perhaps the pricetag of a digital vac gauge becomes more appealing, but that's really just a case of personal opinion or situation.

If the 200€ are too much to spend for equipment it might be better to do wet layup. Otherwise you will spend more money soon on wasted materials.

Hi guys I have read a lot about resin infusion in the forum and other sites, I am a beginner and I have come to the conclusion that I need a digital pressure gauge to save time and materials due to my lack of knowledge. My question is which one do you recommend the model to me Vac Checker, or the GDH 200-14 model are both similar in price, well I hope your help and sorry for my English I am from Spain.