Pump question

[B. Pearcy]

I do not have any experience with pumps, but I've managed to hook mine up and it is working fine. I do have one concern though.  If my fish tank empties to the point of shutting off the pump, what is the likelihood that it will come back on? Will it just burn itself up? 

I have my pump elevated 12 inches from the bottom of my 210 gallon fish tank so that it will never pump itself completely dry. However, assuming the worst, suppose my pump doesn't shutoff as expected and continues to pump until the water level is below the pump's ability to continue pumping?

I realize the risk is reduced when you use a bigger fish tank, but that wasn't an option for me due to the larger footprint involved.

Anyone care to help out the new guy once again?

I didn't think I'd need one, but is this a case where an index valve could be helpful?

For reference, my 2 growbeds are 100 gallons each filled with 1/2 and 3/4 inch river gravel (mostly 3/4 inch). The pump is a Quiet One 4000.

I also do not have all the media in the grow beds yet, so this issue might take care of itself. The gravel washing is a long tedious process for me so I couldn't resist "testing" the pump a little bit here and there.  I guess I should wait on the "testing" (i.e. playing) until I get all the media in the beds. 

When I planned the system I always assumed there would always be at least 100 gallons left in the fish tank when the grow beds were pumped full of water (2 inches from the top). I do have an over flow plumbed into the grow beds which I can adjust a total of 4 inches down.

Again, my understanding is that the object is to flood the grow bed as full as possible. I've read some conflicting explanations of this too, but if water is not reaching the plant roots I'd expect some dead plants eventually.

[TCLynx]

The quiet one 4000 pumps I don't expect to burn up just sucking a little air (I've been abusing the one in my duck system for months) and by the way they don't pump water as well as they start to suck air so the water level in a fish tank is not going to drop as fast as soon as your pump is getting a little gas so to speak.

 

But, I don't expect you will see real issues once you get most of your media washed.  In a system with 200 gallons of fish tank you should easily be able to deal with flooding and draining 200 gallons of grow beds.  Just set your overflows as low as you can until the media is up to full height.  I would finish filling one so you can get it planted out properly and then finish filling the other then get the overflow set properly.

 

You want to expose as much gravel as you can to water for bio-filter purposes but you definitely want to keep most of the very top surface of the gravel from being constantly wet and definitely don't flood water over top of the gravel for the sake of most types of plants.  (water plants like watercress being an exception.)

 

Now if you have a major plumbing leak (as in the pump removing water from the fish tank and pumping it all over the grass instead of into your grow beds, you are likely to burn up most pumps.  I'm not sure how well the QP40000 will recover from overheating to the point of shut off it a true run dry situation but such a thing will definitely shorten most pump life but the point of raising the pump up off the bottom is so you don't kill all the fish along with burning up the pump which could happen in such a situation.

 

 

[B. Pearcy]

Thanks for the reassurance. I will get back to washing gravel again tomorrow. I had to rest tonight (lol).