Here a good read...
http://www.lifereef.com/siphon.html
Why risk thousands of dollars of fish, corals, livestock, flood damage and cleanup on a $69.00 prefilter box or any other prefilter box of questionable reliability, and there are many.
Not a single failure since this prefilter went on the market over two decades ago! If it were not for the cheap copies of Lifereef prefilter boxes (though not copied exact otherwise they'd be reliable) and the ones that are called "tubeless" the Lifereef prefilter box would not have to be defended every time one was sold.
Absolutely the finest and most reliable prefilter box in use today! Why not be 100 percent sure of a no-failure than go with any other with a guaranteed failure or poor performance.
Will not lose water from siphon tube when power goes out!
Will automatically START FLOWING WATER when power comes back on!!!
Any prefilter that uses an Aqua Lifter pump or similar, WILL FAIL!
It is the cheap copies and "tubeless" designs that have given all prefilter boxes a bad reputation.
Prefilters for standard aquariums, EuroBrace rims, Red Sea Max, and BioCube, and custom too!
Not a single failure since the Lifereef Prefilter Box came on the market over 25 years ago!
Thousands sold, not one flood or failure! No cheap "suck-pump" required! Nothing to break down or wear out! No fittings to leak causing loss of siphon and flooding! Your main system pump is all that is needed, and all sump setups have a return pump. NO SECONDARY CHEAP PUMP THAT WILL FAIL IS NEEDED!
Since 1988 this prefilter has allowed the hobbyist to safely deliver water from the aquarium to the sump without fear of failure and readily resumes safe operation after a power outage, GUARANTEED!
In the 24 years that the Lifereef Prefilter Box has been sold not one has failed to re-start when the power comes back on or has failed while in operation! This is not the case with others using built-in siphon walls ("tubeless designs") which are prone to failure while in operation and prone to failure upon power coming back on. The majority of prefilter boxes I sell are to those with the tubeless design, and usually after a FLOOD! Why even risk it? The others don't want to risk it and replace their tubeless design with a Lifereef.
Tubeless designs (built-in siphon wall) are of the poorest design and their use comes with considerable risk of FLOOD! If you use one of these you are guaranteed to have a FLOOD, no matter how careful you are! These prefilters rely on a cheap $15.00 "suck-pump" to keep them working, and this pump will fail, then the prefilter will FLOOD your aquarium or your sump! This "suck-pump" can fail even while your main pump is working and cause major aquarium flooding or even fail to come on when power resumes. These prefilters are DISASTERS waiting to happen!
IF YOU GET A TUBELESS DESIGN YOU MIGHT ALSO PURCHASE A WET-VAC, IT WILL BE NEEDED.
Don't risk it! They are also impossible to clean the siphon wall and if the siphon wall is black algae will still grow as will tubeworms and other calcium building animals and you cannot clean this area. Micro-bubble are always a problem too due to the "suck pump" pumping them into your aquarium.
Another competing prefilter box which is almost an identical COPY of the Lifereef has two flaws that need to be addressed: 1. The inner box can be knocked out of alignment allowing three to four inches of your aquarium water to suddenly rush into your sump and OVERFLOW your sump. 2. Their inner box has less slots for the water to flow through which means you need an extra large sump to hold the extra water that will drain when power goes out. Less slots means your aquarium will rise higher on the slots at a given flow rate. With their prefilter you will not be able to move as many gph without raising your aquarium water much higher, and thus more water will drain back into your sump. You will be able to use LESS water out of your sump being pumped back into the aquarium for the same flow rate using a Lifereef Prefilter. Cheap may get you a similar product but it does not have the same proven characteristics and qualities as a Lifereef Prefilter. And why risk your costly investment for the sake of a few dollars, just doesn't make sense.
Do a search, you will not find a hobbyist who has had a Lifereef Prefilter Box fail. Then check the others, you will find numerous failures. So, why risk a flood and the $$$ damage caused by water, using an inferior design that might look SIMILAR but does not offer the safety and quality of a Lifereef.