A siphon break can save you from disaster....

Sk8r · 03/15/2020, 10:37 AM

Snulma reminds me there is one item all new water-hobbyists need to know and watch for.

A hose that touches the water at both ends can become a siphon---transporting water you don't want transported. Let me give you an illo re how sneaky that can be: I had a big topoff reservoir, an autotopoff unit, and a hose that was about 1.5" above the sump water line, safe, right?

Not so much so when I had a power out (brief) and the hose touched the sump water as the water rose in there. Just a little airline tubing, a lot of gallons...no big deal, eh? Well, the siphon started sucking and the fill began to exceed the proper limit in the sump, because a siphon just siphons. And it does it in either direction. When the siphon filled the sump enough, it stalled, but the deficit was now on the other end of the siphon, so it back-flowed. Wash. Rinse. Repeat. A lot. And remember one side is proper salt water, and the other is fresh water.

Over time, that siphon dropped the salinity in my display tank and salted my freshwater topoff, trading water back and forth, back and forth. Every time the sump got low, the autotopoff started to pump fresh water in, and every time it cut off, the siphon took sump water back to the freshwater storage.

Fortunately I figured it out before any fish died. I then raised the salinity back to 1.024 slowly and carefully.

What would have prevented this?Either keeping the free end of the hose ABOVE the potential flood limit in a power out---or putting a hole in the highest arch of the siphon hose so it would release the suction and not backflow.

Siphonage is a tricksy thing. You have to do some thinking as to how much clearance is enough. And remember---that pump you leave lying in a bucket on the floor, with a hose IN your (higher) tank---becomes a siphon itself, the minute you cut the power, and one with a half-inch hose, to boot. More than one hobbyist has gotten that surprise.

cvrle1 · 03/15/2020, 11:19 AM

Always tricky trying to prevent floods due to this. I am in the process of setting up 2nd tank now, and will have to do trial and error on power outages to make sure sump has enough room for all the water coming back.

One thing I will say is that those check valves shouldnt be counted on. They tend to clog up and not work when you need them the most. As long as sump has enough room, thats all one should need.

Sk8r · 03/15/2020, 11:53 AM

Check valves are a flood waiting to happen in a living tank system. Sooner or later, be it a snail or a wad of weed, they will betray you.

cvrle1 · 03/15/2020, 12:03 PM

One thing I was looking into is what Melev did with check valves, he reversed them, so he used them as siphon break. Perhaps that could be good way of using them as they are out of the water.

https://www.youtube.com/watch?v=TdURonoCyZM

snulma1 · 03/20/2020, 03:28 PM

Quote:

Originally Posted by Sk8r

Check valves are a flood waiting to happen in a living tank system. Sooner or later, be it a snail or a wad of weed, they will betray you.

I personally like to place a check valve yet plan for them to fail. I know its money that could be spent elsewhere but its an additional line to prevent a disaster.
If it does fail, I then usually have my siphon break in place!

03/15/2020, 10:37 AM	#1
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	A siphon break can save you from disaster.... Snulma reminds me there is one item all new water-hobbyists need to know and watch for. A hose that touches the water at both ends can become a siphon---transporting water you don't want transported. Let me give you an illo re how sneaky that can be: I had a big topoff reservoir, an autotopoff unit, and a hose that was about 1.5" above the sump water line, safe, right? Not so much so when I had a power out (brief) and the hose touched the sump water as the water rose in there. Just a little airline tubing, a lot of gallons...no big deal, eh? Well, the siphon started sucking and the fill began to exceed the proper limit in the sump, because a siphon just siphons. And it does it in either direction. When the siphon filled the sump enough, it stalled, but the deficit was now on the other end of the siphon, so it back-flowed. Wash. Rinse. Repeat. A lot. And remember one side is proper salt water, and the other is fresh water. Over time, that siphon dropped the salinity in my display tank and salted my freshwater topoff, trading water back and forth, back and forth. Every time the sump got low, the autotopoff started to pump fresh water in, and every time it cut off, the siphon took sump water back to the freshwater storage. Fortunately I figured it out before any fish died. I then raised the salinity back to 1.024 slowly and carefully. What would have prevented this?Either keeping the free end of the hose ABOVE the potential flood limit in a power out---or putting a hole in the highest arch of the siphon hose so it would release the suction and not backflow. Siphonage is a tricksy thing. You have to do some thinking as to how much clearance is enough. And remember---that pump you leave lying in a bucket on the floor, with a hose IN your (higher) tank---becomes a siphon itself, the minute you cut the power, and one with a half-inch hose, to boot. More than one hobbyist has gotten that surprise. __________________ Sk8r Salinity 1.024-6; alkalinity 8.3-9.3 on KH scale; calcium 420; magnesium 1300, temp 78-80, nitrate .2. Ammonia 0. No filters: lps tank. Alk and cal won't rise if mg is low. Current Tank Info: 105g AquaVim wedge, yellow tang, sailfin blenny,royal gramma, ocellaris clown pair, yellow watchman, 100 microceriths, 25 tiny hermits, a 4" conch, 1" nassarius, recovering from 2 year hiatus with daily water change of 10%.

03/15/2020, 11:53 AM	#3
Sk8r RC Mod Join Date: Feb 2006 Location: Spokane WA Posts: 34,628 Blog Entries: 55	Check valves are a flood waiting to happen in a living tank system. Sooner or later, be it a snail or a wad of weed, they will betray you. __________________ Sk8r Salinity 1.024-6; alkalinity 8.3-9.3 on KH scale; calcium 420; magnesium 1300, temp 78-80, nitrate .2. Ammonia 0. No filters: lps tank. Alk and cal won't rise if mg is low. Current Tank Info: 105g AquaVim wedge, yellow tang, sailfin blenny,royal gramma, ocellaris clown pair, yellow watchman, 100 microceriths, 25 tiny hermits, a 4" conch, 1" nassarius, recovering from 2 year hiatus with daily water change of 10%.

03/15/2020, 11:19 AM	#2
cvrle1 Registered Member Join Date: Nov 2000 Location: Surrey, BC Posts: 454	Always tricky trying to prevent floods due to this. I am in the process of setting up 2nd tank now, and will have to do trial and error on power outages to make sure sump has enough room for all the water coming back. One thing I will say is that those check valves shouldnt be counted on. They tend to clog up and not work when you need them the most. As long as sump has enough room, thats all one should need.

03/15/2020, 12:03 PM	#4
cvrle1 Registered Member Join Date: Nov 2000 Location: Surrey, BC Posts: 454	One thing I was looking into is what Melev did with check valves, he reversed them, so he used them as siphon break. Perhaps that could be good way of using them as they are out of the water. https://www.youtube.com/watch?v=TdURonoCyZM