Richard,
Just thought I'd add some info about modifying pumps. I'm sure you already checked out potential problems but I didn't see any comments in the article.
Pumps and motors are designed as a unit with the motor chosen such that its power output matches the power requirements of the pump to which it's coupled. The modification you write about is essentially changing out a pump but still using the same motor. There is a very good chance the propeller is moving much more water than the original pump and is therefore drawing considerably more power. If this is so, the motor is likely being over driven and may be producing more heat than its designed to handle. I assume the change out has been tested for some time and no problems have been observed so no mention of said possibility has been made. However, other hobbyists may take the idea further and modify other power heads with a smaller motor safety factor. This could result in a failure of the motor and most of us really don't want to fry a power head in our reefs. Hence I present the warning here.
Also, since the modified pump is in all likely hood moving much more water than prior to the modification some of the effects you observed were likely due to the increase in overall water movement and not due only to a change in the flow pattern. Not to say this is bad, but it is likely happening. If no long term issues occur with the motor, it seems like a nice little power head upgrade.
Finally, it is also fairly easy to add a nozzle on the end of a power head to change the flow pattern from tight to wide. The simplest is just to add a larger diameter pipe to the end of the power head. Even better is a larger diameter pipe that is open on the sides so that the forward motion of the higher velocity tight stream pulls in water from the sides. This converts some of the pressure energy of the pump into flow energy in the form of more water moving at a lower velocity. Of course, this nozzle arrangement will not change the actual amount of water going through the power head so the pump will not be over driven. The propeller modification will almost certainly make the most total flow.
It would be interesting to see the power draw of the pump before and after the modification.
Anyway, thanks for the article and the info it contains,
Tracy Gray
Just thought I'd add some info about modifying pumps. I'm sure you already checked out potential problems but I didn't see any comments in the article.
Pumps and motors are designed as a unit with the motor chosen such that its power output matches the power requirements of the pump to which it's coupled. The modification you write about is essentially changing out a pump but still using the same motor. There is a very good chance the propeller is moving much more water than the original pump and is therefore drawing considerably more power. If this is so, the motor is likely being over driven and may be producing more heat than its designed to handle. I assume the change out has been tested for some time and no problems have been observed so no mention of said possibility has been made. However, other hobbyists may take the idea further and modify other power heads with a smaller motor safety factor. This could result in a failure of the motor and most of us really don't want to fry a power head in our reefs. Hence I present the warning here.
Also, since the modified pump is in all likely hood moving much more water than prior to the modification some of the effects you observed were likely due to the increase in overall water movement and not due only to a change in the flow pattern. Not to say this is bad, but it is likely happening. If no long term issues occur with the motor, it seems like a nice little power head upgrade.
Finally, it is also fairly easy to add a nozzle on the end of a power head to change the flow pattern from tight to wide. The simplest is just to add a larger diameter pipe to the end of the power head. Even better is a larger diameter pipe that is open on the sides so that the forward motion of the higher velocity tight stream pulls in water from the sides. This converts some of the pressure energy of the pump into flow energy in the form of more water moving at a lower velocity. Of course, this nozzle arrangement will not change the actual amount of water going through the power head so the pump will not be over driven. The propeller modification will almost certainly make the most total flow.
It would be interesting to see the power draw of the pump before and after the modification.
Anyway, thanks for the article and the info it contains,
Tracy Gray