How strong should my pump be?

I have ahomemade aeroponics system. It is made of a rubbermaid tote with two pvc's going across the middle with 4 360 misters for 4 plants. Now, these misters are rated for 7 gph. 4 misters is 28 gph, gallon per hour, but the mist is very weak. Ive used a 60 gph and 70 gph, and even put them both together for 130 gph, but stil wont spray right. What should i do

I have never used them but it sounds like you need to adjust the flow or bet more pressure. can you adjust the nozzles?

GPH doesn't necessarily equal pressure, nor do I believe combining them equals 130 GPH because of the pressure issue I believe you have.

I suggest getting a more powerful pump and regulate the flow with a valve and a "T" fitting. TIP: If you put the valve after the T (in nutrient rez) the excess pressure of the more powerful pump will circulate/airate your reservoir also.