For one ebb and flow table 1.1 meter x 1.1 meter (43 inch x 43 inch) with a reservoir directly underneath I need a pump. I will use rockwool cubes for SOG.
Never done hydro before, so I never had to buy pumps before.
The pond and sump pumps come in too many varieties… 
Which specs does the pump do to have?
a 250 gph pump should be plenty. you can probably get away with smaller than that if you wanted to
Buy an aquarium pump, 150-200 GPH or so. Get the biggest reservoir you can. 70 gallon reservoir would be excellent, 100 gallon even better. Less swings in nutrient concentration/pH and longer between top-offs.
Run bleach in your reservoir; it’ll help keep things clean. Use mineral salts only in the reservoir, no additives other than nutrients and bleach and maybe peroxide. DynaGro, GH Flora Series, Maxi Series, etc.
Keep your reservoir cool and aerated. A powerhead pump, and a large airstone in your reservoir will keep your water quality high. Water quality is everything in active hydroponics. I recommend rockwool mini-cubes in small pots over solid blocks of rockwool. Less of a margin for error, since they have quite a lot more air than the solid blocks.
For how many minutes would you flood the table? And how high?
The aquarium pumps do they cause lot of vibration or are the on rubber feets?
I looked the sump pumps up and they are even cheaper than the aquarium pumps and have a lot more wattage…???
If I take a sump pump, the water will shoot like a fountain out of the inlet of the table???
Use an aquarium or hydroponic supply pump, sump isn’t what you need, and aren’t for continued use.
There’s a lot of different opinions on flooding, but 15 minutes 2-3 times a day is good. In heavy flower you will probably will have to flood 3-4 times a day since the plants are consuming more nutrient solution. This’ll depend on a lot of factors, chiefly what substrate/media you choose, how big the plants are, etc. In a roundabout way, you’ll flood enough times to keep the media moist. Flood height should be about halfway up the pots. So if you have a pot that’s 8" high, flood about 4" high.
If you use big pots and a lot of media, you may only have to flood 1-2 times a day. The more flood/dry cycles and the more air in the media, the faster/heavier your rate of growth, but also a lower margin of error, such as if a pump fails and the plants need a flood cycle every 3 hours you could be looking at dead plants in less than a day. Using more media and less flood cycles means they don’t dry out as quickly and thus you have a greater chance of catching a failure.
Thank you very much. How often do these pumps fail???
Are there pumps (brands) which dont or only rarely fail?
Not very often. Never happened to me. But just often enough for you to be wary. There’s only 1 moving part in ebb and flow, so it’s the most fail-proof form of active hydroponics.
Eheim makes great pumps for reasonable prices.
Any brand-name hydro store pump will be fine, just don’t get a cheap aquarium pump from Wal-Mart and you’ll be fine.
what is the problem with sump pumps?
My hydroponic pump (good quality and not cheap) failed, what almost caused to kill all plants including mother plants…
With my sump pump I never had a single failure in more than double the time. But I am not sure if the sump pump is rusting inside and is harming the plants.
I am searching for a heavy quality pump, preferably sump pump (because almost no noise with them) which is safe for plants, doesn’t emits any metals or oils or whatever.
Any idea?
Hey SamandMax, sump pumps can be more pump than you need. Unless you got a big op, most of what I looked at was up past 1000 gallons per hour.
If I was going that route, I’d look into the Little Giant lines, as their submersible sucks from the base, so it will not leave much solution in the resy.
I’m close to a That Fish Place, that has lots of pumps to choose from, so I do not really remember all the names of the various makers of pumps anymore. Good luck in your search.
I use these valves (see image). A strong pump with these is not problem. My table is flooded enough with the strong pump in 3 minutes
I’ve got a 4x4 table, 40 gallon reservoir. The pump is 250gph and isn’t big enough. Doesn’t flood the whole table completely before the timer cuts & pumping the old nutrients is slow.
I bought an 800 gph that can be adjusted down that I think will work perfectly.
Buy bigger that what you need and cut it down.
So, why does your timer cut out before it’s done flooding the table? They are adjustable you should know? 
