As an interim measure, would your gravity feed work through a mechanical float valve? If you can do gravity, then why bother with electrics at all. I don't have a sump & impractical to raise display top off container above the tank for gravity, so I use an air pump on a timer to pressurize a wine carboy full of water. The air pressure pushes water through a mechanical float valve (Wait brand for furnace humidifiers) into the display. This has worked very well for 4-5 years now.

As far as relays, you might be able to get one at an Auto parts store or Canadian Tire. Many 12 VDC relays for the automotive or marine industry are rated to 120 volts. You do need to check the specs though, they're not all compatible. Voltage & current info is usually on the relay & packaging but you might need to use a 12 volt power supply to run the coil of the relay. Chances are you'll have a few of those around the house. Speaking of which, if you have any old, defunct appliances kicking around, chances are there's a relay or two in one of them you can scavenge.

Those pumps really don't do well running dry for any periods of time. Does this happen often to yours?

The Wait float valves are great, I've used them for topup for close to 15 years now on other tanks and there hasn't been any failure with them other than blocked lines or human error. KISS principle is better sometmes!

But on this tank, the topup enters the tank by being injected into the skimmer air intake. This has the added value that I don't ever need to clean the venturi. Two years in on this skimmer and every time I inspect the venturi it's sparkly clean. Every other skimmer I've had to do vinegar baths on the venturi's every couple of months so I know this is working.

I have a 12vdc solenoid valve coming from an ebay vendor but I have doubts it will get to me in time before I have to go away for a few days this weekend. Thus the need for something in the interim.

Tough call though. If it's $40 for a relay, I'd be further ahead to just find a LFS in town with the Tunze pumps in stock and pay $25 instead. :neutral:

I was sort of hoping a relay would be more like $5. :lol: Oh well. Shows you what I know..

It happened once on the new pump. That's probably what did it in then.

I like the idea of a valve better than a pump. Easy enough path forward just not in time for the weekend.

i'd just grab a tunze pump for the peace of mind. that or find a human top off for the weekend. i'm away this weekend as well fyi lol. i'm actually getting both tanks ATOs working tonight myself.

Well .. yeah, if it's $40 for a relay ...... yeah, this idea is dead for now. Le sigh. Hopefully I can find me a Tunze pump at lunchtime... Of course Murphy's Law says that what's going to happen is the only store that will have one on the shelf will be the one who sells it for $80. Win!

I once ordered a transformer from Active over the phone and the guy on the phone asked me like 3 times if I was sure I wanted it shipped to me. I didn't understand why until I was driving around up north that weekend and my wife is like... isn't that the place you just ordered from!? they're right in town!