While there are no rules, there are guidelines that have built up. The most common guideline I've seen on TFF for this is 5x turnover. For your 30 gallon then, then, the guideline would recommend a turnover rate of 150 gallons per hour, with perhaps 200 as the upper end.
Common exceptions to this guideline are appropriate I believe when keeping tanks overstocked with large and/or messy fish or when running a high-tech planted tank. In fact, one sees unusual considerations from the planted tank hobbyists in that sometimes below average turnover rate is desired, for less water movement and sometimes up to 10x turnover is recommended because of CO2 or other considerations. Another exception happens when species-specific tanks are kept where it is known that the species perfer fast-moving streams or rivers, for example.
The filter you are considering, with more than twice the flow rate normally recommended, should be thought about carefully. Does it really have an effective flow adjustment? Does throttling the flow rate down have a negative effect on the life of the pump head? If you don't adjust it down, it could behave like a little fire-hose in your 30G tank. I'm not saying it won't be fine, as it may have excellent down-adjustment, and that may be just fine to use and not effect the life of the pump motor. I'm just saying you might rest easier if you check these things out and be prepared.
I don't mean to sound excessively conservative, as I agree with Corleone that there is no such thing, theoretically, as too much filtration (witness the acres of natural filtration per fish in the wild, its huge!) And much can be done with spray bar redirection. I just want you to be armed with the complete picture so that you have a chance at feeling more fully satisfied that you've thought through the options.
~~waterdrop~~
Using the valve after the pump keeps the input pressure to the pump at working pressure, thus keeping wear "normal".
