Floating / Variable Overflow to Connect Two Ponds?

[esvenson]

I'm a pond newbie, but have kept reef / planted tanks for years. I recently converted an outdoor water feature into an eco pond. The water volume is ~125 gallons with a waterfall ~5 feet above the main pool. Because of the relatively large waterfall (compared to the pool size) and because I run it 24/7, the pool loses 0.5-1.0 inch per day. I assume this is because the waterfall accelerates evaporation, but I didn't set up the pond in the first place, so a slow leak or sloppy pond liner installation are also possible. As a water feature running only a few hours a day, the relatively fast evaporation wasn't as big of an issue.

To alleviate the need to top up my pond every couple days, I'm considering adding a second pond (planter box style) next to / above the main pond to serve as an auto top off reservoir. The easiest thing to do is to have the reservoir pond be a separate system with plants and critters that can handle larger water level changes. Then I would use an auto top off system in the main pool to pull from the reservoir and I'd top off the reservoir once per week.

What I would love to do is connect the two systems, so the new pond serves as both an auto top off reservoir and an additional plant/bog filter. The problem is, if the reservoir overflow is fixed, then the water level in the reservoir will stay constant and the water level in the main pond will continue to fluctuate. I need to figure out how to make the reservoir overflow adjust so the water coming into the reservoir matches the water falling back to the main pond - regardless of the water level in the reservoir. If I figure this out, I can connect the two systems and still top up my main pool from the reservoir.

The DIY ideas I've come up with so far all have some failure scenarios that either have the main pond draining up into the reservoir, causing the reservoir to overflow. Or the reservoir draining completely into the main pond, causing the main pond to overflow. I feel like there should be an off-the-shelf plumbing product for this - maybe for a different application. I'm also not the first person to think of this, so there might be DIY plans floating around somewhere?

Would love your thoughts!

 

[j.w]

Don't know how to do your project described but others here can help.

 

[hamstermann]

Something like this auto-fill valve at Amazon??

It works like a toilet tank fill valve - when the water line drops a certain amount, the bulb drops, opening the valve to let water in until the float gets to a certain point and it shuts off the water again.

You could put one in the lower pond to water in from the upper pond, and one in the upper pond to let water in from a waterline connection, or you could just put one in the lower pond that's hooked directly to your water line connection.

This video shows you how to install them:

 

[JRS]

Welcome to the forum. I'd agree with the high evaporation rate from the waterfall, especially with such a small sump. If you are thinking an ATO anyways, not sure why you would involve the bog as reservoir, just use your main sump. Is there a problem connecting to a water supply?

 

[esvenson]

Something like this auto-fill valve at Amazon??

It works like a toilet tank fill valve - when the water line drops a certain amount, the bulb drops, opening the valve to let water in until the float gets to a certain point and it shuts off the water again.

You could put one in the lower pond to water in from the upper pond, and one in the upper pond to let water in from a waterline connection, or you could just put one in the lower pond that's hooked directly to your water line connection.

This video shows you how to install them:

This is a fabulous idea! I never considered topping up the top up pond, but that would work. I guess I'd need to watch everything in action to make sure that one of the ponds wasn't filling up faster than the other, but I guess the main pool would only pull from the reservoir when it needed to and the reservoir would only pull from the water line when it needed to. Even if the water levels weren't totally constant minute-by-minute, over a 24 hour period things would be in balance.

I'll think more about this and report back with the results!

 

[esvenson]

Welcome to the forum. I'd agree with the high evaporation rate from the waterfall, especially with such a small sump. If you are thinking an ATO anyways, not sure why you would involve the bog as reservoir, just use your main sump. Is there a problem connecting to a water supply?

The only "problem" with connecting the main pond to the water supply is that I wouldn't have an excuse to set up another pond.

 

[JRS]

A nice bog filter will help mitigate algae as well as promoting system stability through increased volume; good enough reason I hope. A constant overflow setup in the bog portion will be much more reliable in the long run I think.

 

[esvenson]

A nice bog filter will help mitigate algae as well as promoting system stability through increased volume; good enough reason I hope. A constant overflow setup in the bog portion will be much more reliable in the long run I think.

Yes. I joked about "excuse to set up another pond" but the algae mitigation and larger water volume were the main consideration. Having kept reef tanks for years, I appreciate the stability that a bigger tank with a big sump provides.

I live in the Bay Area, so it doesn't get extremely cold in the winter, but I also thought it would be good to have the flexibility to keep different fish in the reservoir that I can move indoors during the winter (ie might be easier to net them out of the reservoir pond). The waterfall might make it hard/expensive to heat the entire system in order to keep more tropical fish in the pond over the winter.

 

[GBBUDD]

Something like this auto-fill valve at Amazon??

It works like a toilet tank fill valve - when the water line drops a certain amount, the bulb drops, opening the valve to let water in until the float gets to a certain point and it shuts off the water again.

You could put one in the lower pond to water in from the upper pond, and one in the upper pond to let water in from a waterline connection, or you could just put one in the lower pond that's hooked directly to your water line connection.

This video shows you how to install them:

There is a second type its a semi sealed barrel only water gets in and the float rises within the tube less chance of algae or other foreign material from clogging the ball.

 

[esvenson]

Update:

I really appreciated all of your advice, and I ended up combining feedback. This falls into the camps of "It takes a village" and "Why didn't I think of that?!"

This is what I did -
1) I added a float valve in my main pond that's hooked up to a timer connected to a main water supply. The timer is set for 10 min each day. So far, the float valve is activated after only a few minutes during the 10 min window. I might add a second timer to protect against the first one failing, but I stare into my pond for hours each day, so I should be able to tell if the existing timer isn't working.

2) That allowed me to connect my second pond with a simple bog filter (pump + overflow) set up.

Problem solved!

I attached pictures of the main pond, the second pond, and a close up of the plumbing (float valve and second pond return hose).

My ~40 rice fish and ~1 billion tadpoles seem quite happy with the extra water volume. And I'm happy because I don't need to top up my pond every other day!