Easy to empty any size tray, no holes, pumps, just a simple system, I should patent it. Well, anyway, you can use any hose, I prefer clear plastic hose, say 1/2 inch size, about 30 inches long.
Submerge the entire hose in the solution, get all the air out by holding down the middle of the hose and let the air escape through the ends. An alternate way is to put a funnel on one side, keep the other side submerged, then pour some of the solution into the hose to fill it, lowering the funnel size into the tray as you get near the top.
Then, keeping the inlet side under the solution, take the other side, with your thumb on the hose to keep air/solution from getting in an out, and lower the hose down into a plastic bucket (the type with a pouring spout for later transfer into a bottle) and release the thumb so the solution then flows. It will siphon the tray solution into the bucket, as long as you keep the hose in the tray below the solution, so no air breaks the siphon.
Hopefully, I describe this so it is understood. Works perfect and have used in when transferring fluids out of large trays.