Auto water change – Could you help me prevent a disaster?

[skydancer]

In order to simulate the ocean cycle in my reef as close as possible to the “real thing�, I have devised this plan to let my Aqua Controller III Pro perform daily water changes at a rate of about 3-4 g/day, times 30 days, it would be about 90-120 g/month or 1/3 of the total water volume in the show tank. (300g reef)

The automatic water change system in its simplest form contains 3 NC solenoid valves, 2 make up tanks and tubing. Yep, that’s it!!!

The set up:
Show tank – 300 gal [abbreviated: (SHOWT)]
A siphoned ¼ inch line is placed about 2.5 ft deep (total SHOWT depth is 3 ft) inside the SHOWT behind the rocks and a NC solenoid valve connects the siphoned line to the drain). The solenoid valve is NC when power is OFF. When the AQ3 PRO opens the solenoid valve for 30 minutes SHOWT saltwater flows into the drain (gravity fed) at a rate of 6g/hr.

RO/DI Fresh Water Make-Up Tank – 10 gallons [abbreviated (FMT)]
This tank is filled directly from the RO/DI unit and there is a shut off valve when full.
There is a NC solenoid valve that the AQ3 PRO turns ON as normal operation for continuous evaporation auto-top off. If power goes OFF the solenoid valve closes. As water evaporates from the SHOWT on a daily basis, the sump level drops, the auto-top off KENT plastic float valve lowers and opens and via gravity RO/DI fresh water re-fills the sump.

RO/DI Saltwater Make-Up Tank – 35 gallons [abbreviated (SWMT)]
When the tank is “low� I open the MANUAL fill valve and the SWMT tank is filled from the same RO/DI unit at a rate of 75g/day. Then I prepare the saltwater and let the RIO2100 mix it up in the SWMT. There also exists a float sensor in the SWMT that rings an alarm (sends me an email) if the SWMT water level is “low� and the water change is skipped for that day. There also exists a NC solenoid valve that the AQ3 PRO turns OFF as normal operation that connects the SWMT to the sump. If power goes OFF the solenoid valve is closed.

Once a day for 30 minutes, the AQ3 PRO turns OFF the FMT solenoid, turns ON the SWMT solenoid, and turns ON the Drain solenoid to the drain and saltwater flows out of the SHOWT. When the sump lowers the auto-top off re-fills the sump with pre made saltwater. When the time expires things go back to normal.

Give it one in a million chance, and it will happen to me. One of my worst nightmares would be to come home one night and find my 300-gal reef empty!!! Here is my million-dollar question. What if a solenoid gets stuck in the open position and the SHOWT water drains past the 35 gal? Even if I have a float sensor it won’t help… other than to email me with an empty sump message! I also thought about doubling up on the solenoids… 2 per line. So if one gets stuck open the other one will close. What if they both get stuck?

Your infinite wisdom on tackling this problem would be most appreciated. I trust all the Reef Central brainpower to come up with a solution for me.

[tekknoschtev]

is there a possibility of drilling the tank so you wouldnt have to siphon over the tank? If not, how about fanagling something like a HOB overflow for the situation, and instead of using the 1" drains, size it down to the 1/4" tubing. That way you dont have the tube so deep in the tank? That way when the water gets low (figure out the height you need for the daily WC) it will stop draining water.

[david8956]

A siphoned ¼ inch line is placed about 2.5 ft deep

Why couldn't you just drill a small hole in this tube an inch or two under the surface? If it ever siphoned water out to that level it will break siphon by sucking in air.

[skydancer]

If I drill a small hole in this tube and the power goes off the water line would drop and the sump fills.

After the water line lowers the siphon would die. Then I would have to start it manually again. Unless I drill the hole below that water line but then the pumps would run dry. I guess I'll have to experiment with it. And it is better to run the pumps dry than ending up with an empty reef!!! LOL

[barryhc]

Originally posted by alexpetropoulos
If I drill a small hole in this tube and the power goes off the water line would drop and the sump fills.

After the water line lowers the siphon would die. Then I would have to start it manually again. Unless I drill the hole below that water line but then the pumps would run dry. I guess I'll have to experiment with it. And it is better to run the pumps dry than ending up with an empty reef!!! LOL

Have the float sensor activate a relay that cuts power to the pumps when the float signal says "low". Install a second float switch if need be. Sounds like a nice system, by the way!

> barryhc

[BeanAnimal]

I know this is not what you want to hear....

but the best way to do this is to use 2 known size resevoirs and a few float switches to latch a few relays. 1 bucket would hold salt water, the other waste water. (it could be done with one bucket but the logic is more involved).

Simple ladder logic would provide the functionality. The I/O of the controller could be used also, but relays alone could take care of the whole thing.

At minimum the only logic needed from your controller is the "start command" to latch the initial relay and start the cycle.

Think of your washing machine if this gets confusing

The tank would drain into a bucket of know size at the start command. Float switches would operate a latching circuit with a solenoid valve. A float valve would also be in series to be an extra failsafe.

Once the bucket is full, the drain solenoid is allowed to open. Once the bucket is empty, the saltwater solenoid is allowed to open and refill the tank from it's bucket.

Once the saltwater bucket is empty, it is refilled from your large saltwater resevoir, and the cycle is ready for the next water change.

Of course the logic would not allow the cycle to start of the saltwater bucket is not full.

The relay logic is rather simple. It's a few latching circuits that are tied together.

This way your taking out a known quantity, only if a know quantity is available to put back. The cycle only repeats if the controller tells it to. The combination of solenoids and float valves prevent a flood.

Bean
Bean

[Randy Holmes-Farley]

I do such automatic water changes with a dual head Reef Filler pump.

[Mimbler1]

I use the dual head reef filler as well - what a great and simple method!

[barryhc]

Originally posted by Mimbler1
I use the dual head reef filler as well - what a great and simple method!

Come on folks, tell us about the "dual head reef filler"!

That's enough "teasing", please. If "we" knew what you were talking about, you wouldn't need to tell us about it, and since you are, "we don't".

> barryhc

[Randy Holmes-Farley]

Champion lighting sells them. It pumps 2 x 30 gallons per day (or less), one in, one out

I mention it in this article:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

from it:

"Continuous water changes: Continuous water changes, despite their name, are not necessarily performed every minute of every day. The distinguishing feature of these changes is that water is added at the same time that it is removed. The actual rate of addition can be high or low. Reef aquarists (myself included) most often perform these types of water changes with two matched pumps, one that removes the old water and one that adds the new water. Often these pumps are part of the same mechanism (such as two sets of tubing on a peristaltic pump or two heads on a diaphragm pump), but that is not a requirement. I use a dual head diaphragm pump capable of a maximum of 30 gallons per day for each head (a Reef Filler pump from Champion Lighting). In my setup, once I have a 44-gallon trash can full of new salt water, all I do to perform a 44 gallon or smaller water change is plug in the pump. The wastewater is sent down the drain. Sometimes I change 44 gallons in one shot, taking about a day and a half. Sometimes I pump for a few hours at a time, and then wait for a few days.

These changes are slightly less efficient than single batch water changes of the same total volume. A continuous water change of 30% exactly matches one batch 26% water change. As with very small batch water changes, these have the advantage of neither stressing the organisms (assuming the change is done reasonably slowly), nor altering the water level in the aquarium. The ease of doing such changes automatically also makes it far more likely that busy or lazy aquarists will actually do them."

[barryhc]

Originally posted by Randy Holmes-Farley
Champion lighting sells them. It pumps 2 x 30 gallons per day (or less), one in, one out

I mention it in this article:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

Yep, daily or continuous water changes are 74% as effective as once a month changes, of the same "total monthly " water change volume( and probably better than that in terms of overall tank parameter stability ).

I guess I'll "google" it! > barryhc

[BeanAnimal]

That beats the dog snot outa my complicated idea. I like the thought even better if a postive displacement pump is used. That way you can be sure both sides are matched (I guess a peristaltic pump is positive displacement).

Bean

[BeanAnimal]

Hey... how quiet are these reef filler pumps?

[Mimbler1]

I don't think you would want it running in a living area. I installed mine in the furnace room where the salt tub resides, and it is quiet enough in there with the door closed. Kind of hard to describe, but to me it sounds like a slow old motor grinding away (maybe canopener loud?, but slower).

[barryhc]

Originally posted by BeanAnimal
Hey... how quiet are these reef filler pumps?

I suspect that some of these pumps could be very quiet indeed. If noise is a problem, it could be fixed quite easily, with a quality design. If I hear any more complaints about "noisy" peristaltic pumps, I will design a quiet one myself.

> barryhc

[BeanAnimal]

From what I can see these are diaphram pumps. Liely gear driven... that is where the noise comes from.

Bean

[Mimbler1]

BeanAnimal,
You are correct,
Mike

[Randy Holmes-Farley]

Mine is noisy, and it is in the basement. It can pump long distances through relatively thin tubing, however.

[BeanAnimal]

Gonna have to build myself a dual component piston pump that operates ate a VERY slow frequency.

Something like 10CC cylinders with a 1 rpm stroke. A small flywheel motor would have enough torque to run the thing and it would be silent. I wonder how long modified glass syringes would last?

Randy, is the pump close to the tank and resevoir? I see that they don't recomend more than a 5' suction head.

Bean

[barryhc]

Originally posted by BeanAnimal
Gonna have to build myself a dual component piston pump that operates ate a VERY slow frequency.

Something like 10CC cylinders with a 1 rpm stroke. A small flywheel motor would have enough torque to run the thing and it would be silent. I wonder how long modified glass syringes would last?

Randy, is the pump close to the tank and resevoir? I see that they don't recomend more than a 5' suction head.

Bean

You are going to need more than 1 rpm. Is 20 CC's per minute enough for you? Syringes are a lot tighter seal than you want. You could cut down the groove that the seal sits in, a little bit to reduce the seal pressure against the glass, without losing the seal on the "rod".

Wrap, or "encase" the glass with something so that it won"t explode from pressure. Wear of the seal against the glass is likely to be a problem. Dry film lubricant might help, but I can't say if it can be made to stick to the glass.

A piston powered pump is going to be very powerful, in terms of "suction head". Just hard plumb the intake, and you won't have a "hose collapse" problem.

I hope this helps. > barryhc

[Randy Holmes-Farley]

Randy, is the pump close to the tank and resevoir? I see that they don't recomend more than a 5' suction head.

It is near the tank, not near the salt water reservoir,which is in another room. I haven't seen a problem with getting water up the tubing.

[Mimbler1]

Although I don't have much of a head to pump on the inlet side, I do have a suction line approx 40 feet long on one head of the pump, (ro/di type tube), and have no problem drawing water,
Mike

[reefclown]

I run a dual head Stenner and it's noisy , what I need is a silent dual head watson marlow, and I mean silent

[BeanAnimal]

barry...

I have pumped millions of pounds of polyuretahane through single and dual component "graco" and "binks" positive displacement piston pumps. The "lowers" of both pumps are almost identicle and rather simple machines. The positive displacement electric paint sprayers at lowes (made by graco) havce small versions of these lowers if you ever get curious as to how sumple they are. The intake and pump on both the forward and reverse stroke.

I had planned on using reinfoced vinyl braid... or 3/8 john guest hose, as it is rather rigid.

Bean

[barryhc]

Originally posted by BeanAnimal
Gonna have to build myself a dual component piston pump that operates ate a VERY slow frequency.

Something like 10CC cylinders with a 1 rpm stroke. A small flywheel motor would have enough torque to run the thing and it would be silent. I wonder how long modified glass syringes would last?

Randy, is the pump close to the tank and resevoir? I see that they don't recomend more than a 5' suction head.

Bean

I was referring to the modified glass syringes, and your concerns about distances. Did I make some kind of error in my response?

You may want to start with something other than glass syringes.

> barryhc