Reef Auto Water Changer RAWC

[bogdanaioane]

Hello everyone,

This is the first time I've ever posted anything on any kind of forum, so please forgive my clumsiness.

I have recently learned of the apex controller and its (quite impressive if I might add) features. After reading quite a bit about it I decided to purchase one for my future reef tank (I'm in the process of sourcing equipment for my fully automated reef system) I'll just take a minute to explain what I mean by fully automated: everything should run on its own except maybe feeding live food to fish (plankton production and dispensing will be automated)

I have been working on this design for the better part of a year now with some aspects of it more difficult than others but now, with my discovery of the apex controller and its programming capabilities I can finally and happily say that I have a working THEORY.
Perhaps I will expand this thread to tackle all the functions of the system but for now I would like to open a discussion about what I found to be the most challenging part in designing this thing which is the AUTOMATED WATER MIXING AND CHANGING function.

Here are the prerequisites that I started with for this system

1. Probably the most important condition imposed is that the tank, its cabinet and its cover are to be regarded as a standalone singular unit with no provision for any additional space in the house/apartment (this means no secondary tanks or tubs anywhere)
2. Supply of water is via pressurized line coming up through the floor into the aquarium cabinet
3. Drain is provided in the floor inside the cabinet
4. Mains 240V AC is provided inside the cabinet

There are off course other conditions but these are the only ones relevant to the design of the REEF-AUTO-WATER-CHANGER. (RAWC)

So let's get to it

THE THEORY:

When water evaporates from your tank (and at quite large rates I might add) you need to top it up with new RO/DI water employing something like a peristalting pump controlled quite easily by the apex controller, or just letting it drip at a controlled rate managed via a solenoid valve. What if you where to add more RO/DI water to your system? Something along the lines of what's required for your tank in terms of new water. Well you will have a problem with your salinity obviously. Then I guess it all comes down to finding a way to dose a controllable amount of dry salt to your system. This comes with the following problems:

A. How do you accurately deliver the salt?
B. How do you completely dissolve it into solution before it reaches the display tank and settles on the corrals burning them, or causes inconsistent salinity readings.
Please share any thought or additional problems that you think there might be relating to this

These problems seamed big at first but after weighing the benefits of this I decided to go ahead and try to come up with something.
Here is what I came up with:

Fresh RO/DI water is constantly supplied to the tank at a rate that replenishes the water to adequate levels. let's call it 5 drops per second. At this rate, deducting an average amount of evaporated water we can ballpark how much salt we would need to add and at what speed. After we determine this we multiply this be a factor of 2 to make sure that our future salt dispensing hardware can definitely cope with our systems needs. At this point we have the "salt output" of the device, let's say 5g per minute.
I have designed the machine that will be able to dispense the required amount of salt and for the purposes of this discussion, let's say that we have a 16mm tube as the output of this device out of which we get a steady flow of dry salt at the required 5g per minute rate. This I believe deals with problem A.

Problem B is I think a bit simpler in that it only requires a bit of customisation of the sump refugium. We dedicate a portion of the sump to a chamber specially designed to immediately dissolve the salt. This chamber will employ a basic moving bed filter that will help stir up the salt, and will be positioned right before the return pump. From simple tests I can say that this should be enough to dissolve the salt completely, but just in case it's not, a multi turn coil can be added to the return pipe that would agitate the water and give the salt that bit of extra time it might need to completely dissolve. A salinity probe can be introduced to the sump somewhere before the moving bed chamber and connected to a PM2 Expansion Box that would control the motor driving the salt dispensing device. All this can be fitted next to the RO/DI unit inside the aquarium cabinet.

This is in broad terms the design and function of the RAWC.

The reason I posted this on this forum is because I think that the Apex is the future of the hobby and it is the only controller that I believe to be capable of running the entire system that I'm currently designing, plus I would also like to hear thoughts and opinions from other members of the community. And who knows, maybe at the end of this we will have designed the first BUDGET RANGE fully automated coral reef aquarium that doesn't even need a separate room for all the guts filters and mixing buckets.

Thanks for reading and hope to hear your thoughts

[gpdno]

Okay, this is also my first shot so let me give it a try. Like you, I am in the process of setting up my new tank. A 150 gal Display with a 45 gal sump/refugium.

I have two separate function that address your problem.

First - Auto-top-off. Water is lost from evaporation and that water (and only water) must be replaced. I have two float switches in my sump. A main - set at theoretical water level and a back-up that is about 50 cm above the main.
Every night at 2 am the system checks the status of the main float switch, if it is on then RO/DI water is added until the switch turns off. In the event the switch fails then the back-up prevents the systems salinity from getting too out of balance.

Second - Auto Water Change. Once a week, immediately following the auto-top-off, a small pump in the sump turns on for 10 minutes. This drains about 40 gal of water from the system (and triggers the main float switch). Then a feed pump adds new saltwater until the main float switch turns off.

I have my RO/DI filter set and two 55 gal drums. The filter keeps the first drum constantly full of pure water. By means of a manual valve and pump I am able to transfer the RO/DI water to the second salt drum. This allows me to have a constant supply of both fresh and salt water to feed both my auto-top-off and auto-water-change systems.

[daquan44]

Using the Apex for ATO and AWC are very simple. I have both and I love it. The only real problem I have not been able to fully automate is adding salt to the AWC container. I have to do that manually. My AWC container is 200 gallons, so adding the salt manually is easy.

[mr9iron]

Using the Apex for ATO and AWC are very simple. I have both and I love it. The only real problem I have not been able to fully automate is adding salt to the AWC container. I have to do that manually. My AWC container is 200 gallons, so adding the salt manually is easy.

Can you post more about your AWC setup including pumps, etc?

[daquan44]

Can you post more about your AWC setup including pumps, etc?

Sure. 1st my ATO. It is very simple. I have a brute trashcan with two 1" bulkheads. One at the bottom with a 1/4" JG fitting and the other a standard 1" pipe. An Aqualifter pump draws the water from the bottom bulkhead and fitting to the Refugium. Inside of the ATO can is a Mag 7 that pumps RODI water to the AWC container using that 2nd bulkhead. My RODI unit uses a BRS float valve kit plumbed to the ATO trashcan. The RODI unit waste water line connects to a pipe that is plumbed into the houses sewage system. A breakout box and two float switches maintain the levels in the sump.
2nd the AWC. I have a 200 gallon Norwesco vertical tank. Inside is a Mag 7 pump plumbed to a 1" bulkhead on the top of the storage tank. The other end of the bulkhead is plumbed to the sump. Their is another 1" bulkhead that receives RODI water from my ATO container. Also inside the tank is a koralia pump I use to mix the saltwater. The Mag 7 pumps are connected to my APEX via the EB8. Every Sunday at 11am the Apex performs a 10% water change to my system. I don't have to lift a finger. In my sump I have a Maxijet 1200 pump that pumps 10% of my tanks saltwater out of the sump into the same pipe that the RODI waste line goes into. Once complete the Mag 7 in the AWC container pumps in new saltwater. Process complete. Besides the 200 gallon Norwesco tank it is a very cheap and easy ATO and AWC. I buy boxes of salt that makes 200 gallons of saltwater. So adding the salt is easy. Open and dump.

[Y-Not]

Maybe it's just me but, it seems that bogdanaioane is over complicating the AWC a wee bit.
Yes, there is a chance that you'll add too much freshwater and dilute your tank's saltwater. If that happens, I suspect you'll have bigger concerns than diluted SW. AKA, water all over the floor.

Assuming your APEX has a salinity probe, use it to shut off the ATO when the salinity has dropped below a certain threshold.
In turn, you'd minimize the dilution of your SW as well as minimize the amount of water you'd have to mop up.

While my set up is technically not an AWC, it's really a constant water change set up.
As X amount is pulled out, a the same time, the same X amount is replenished every 15 minutes, every day, every week.
On my 66g tank this equates to 15 gallon water change every week.

All the while, my ATO is still in place, replacing any evaporated water.

It’s a beautiful thing.
I’m pulling out pollutants at about the same rate as the livestock are adding them.

Zero Nitrates. Zero Phosphates. Happy healthy fish and corals.

- - - Updated - - -

BTW, sorry to have dug up an old thread.

[Kyevey]

While my set up is technically not an AWC, it's really a constant water change set up.
As X amount is pulled out, a the same time, the same X amount is replenished every 15 minutes, every day, every week.
On my 66g tank this equates to 15 gallon water change every week.

I've been looking to put the same thing in place. If you don't mind me asking, what equipment do you use to accomplish in your 'constant water change' setup?