Auto top off *plus* auto water change controller

[Glass World]

Now that I've moved and have a tank room in the basement with a big sump and a lot of space I'm trying to find new ways to automate things. I know people have made auto water change devices before and I'm looking at making one box to control my auto top off as well as an auto water change. If this works out I'll make the schematic available here and possibly (depending on time constrants) build some devices for others.

In any case, What I'm picturing is a system with two large water reserviors (I'm thinking 32G rubbermaid trash cans) one full of fresh water and one with saltwater. I'll have a small powerhead in the bottom of the saltwater reservior to help mix the salt and keep the water circulating. The controller will be a little box with several plugs for small pumps, several lights to monitor the status of the system and the water level in the reserviors and a button to initiate a water change. (I'm also planning on putting contacts in for an external switch or an X-10 universal module). The controller will use a float switch to monitor the water level in the sump and add fresh water as needed. The controller will also do a complete water change at the touch of a button. It can change as much or as little water as you desire and the amount to be changed will be set by the locations of a series of float switches.

When the water change button is pressed (or an X-10 universal module initiates a water change) the controller will disable the auto-top off system, then activate a pump in the sump which will pump water down the drain until the water level in the sump reaches the lower float switch. This will shut off the drain pump and activate a pump in the salt water reservior which will fill the sump with salt water until it reaches the upper float switch (the same one it uses for the auto top off). Finally the auto-top off system will be re-enabled.

The system will have tri color LEDs to show the status of both reserviors as full, low, or empty. If the salt water reservior is empty it will not start a water change since we don't want it drain water from the sump that it can't replace. If the fresh water reservior is empty it won't try to activate the top off pump so we don't burn it out.

The system will also have a backup high level and low level float switch in the sump. If the water level reaches either of those switches it will disable the system so that we don't totally drain the tank or cause a flood.

When the saltwater reservior is empty you will be able to press an additional button on the controller to tell it to fill the saltwater reservior with fresh water. Then you can simply dump in enough salt to match the salinity of your tank and walk away.

My questions are this...

Is this something people would be interested it? Obviously it won't work for some people because of the space required for the reserviors. Additionally you need to have enough 'extra' water in your sump that you can drain all the water for a water change without your return pump running dry. If you have a small sump under the tank and you want to change 10 or 15 gallons this may not be possible. On the other hand, I anticipate using this system to do a 2 or 3 gallon water change daily... for something like that you shouldn't have a problem with draining the sump.

Finally, are there any other usability or convenience features that people would like to see added? Honestly I'd love for it to be able to refill the salt water reservior and add enough salt automatically, but I can't really think of a reliable (and inexpensive) way to accurately measure the salt... not to mention that it needs to be stored in an airtight container. Still, if I change two gallons a day and have a 32G reservior that means that I only need to add salt twice a month... even I can probably handle that;)

Thanks:)

[djrab52]

Glass World,

I am totally interested since I posted a thread about some type of system to help my girlfriend do this while I am away......http://archive.reefcentral.com/forums/showthread.php?threadid=315530&goto=newpost

Definitely keep me posted.....:D

[Xjinn]

you guys know that lots of small water changes over time is roughly equivalent to the same waterchange at larger intervals?


been a while since i calculated but 50% waterchange over a month with infinitely small sizes is like 40% instead of 50%

but an 20% waterchange over a month is as good as an 19% or 18%


so i think you see where it goes.... a dual output dosing pump means even less work, and less shock to tank

[BeanAnimal]

If it helps, I have designed such a circuit for my automated system here at home. In reality it is just two auto topp off systems connected by a dpdt realy to select which "resevoir to top-off from and of course a "bilge pump" to drain the sump to the desired level. I actually have more relay circuits for the resevoirs themselves. I have so many relays that my closet is going to look like an elevator mechanical room. IN any cae, my design will be moving to solid state in its final phase and have 2 state ouputs for each float for digital I/O with the computer or PLC also.

My tank is next to my house sump pump, and I am considering draining the water right into that thing. I am not sure if that is a good idea or not (oder algea growth) but I may do it anyway as it is the only close by drain in the basement.

Bill

[laddy00]

Xjinn
Are you talking about the idea of dilution and that three 10 gallon water changes are not the same as one 30 gal. If not please clarify

[H20ENG]

Sounds cool, but I usually blow and vacuum the detritus when doing the waterchange.
Bean, I got a PLC! Still reading, trying to learn its language.

[BeanAnimal]

laugh one more language to learn! How much ya pay for it?

[H20ENG]

Yup, at least its windows based software. I'm no expert at RLL, but at least what I'm doing with it is not too complicated.
Traded some work to a friend ;)

[Xjinn]

.

[Xjinn]

Originally posted by laddy00
Xjinn
Are you talking about the idea of dilution and that three 10 gallon water changes are not the same as one 30 gal. If not please clarify

i was talking about how they are extremely close to being the same

i got my notes back out on the subject....

quick version is that you could do one 50% water change and have dilution of .50
or two 25% water changes and have dilution of .5625 (.75)^2
or four water changes and have dilution of .586 (.875)^4

this goes as the relation (1 - size/n)^n, and for large n can nicely be written [(n-1)/n]^n(size)

for a 50% water change, infinite n, you get .6065 dilution
for a 25% water change, .7788 dilution
for a 20% change, .8187 dilution
for a 10% change, .9048 dilution

i also wrote a little computer simulation that shows (with scaling completely made up) amount of detrius in the reef starting at 0 for time 0, increasing at a constant rate, and having a large dilution done at large intervals, or equivalently small dilutions at small intervals

it shows the concentrations increasing and leveling off, with jagged spikes at each change

the small interval has a slightly higher average concentration, but the peak levels (right before water change) is exactly the same as if doing larger dilutions


i personally think its how water changes should be done for any substation size tank.... only equipment is a salt water reservoir and a dual output dosing pump (one in, and one to drain), the corals dont get the water condition flux and pull in the day of the water change, no heating required for the changed water etc....

only drawback i see is like h20eng said, blowing detrius off the rockwork before doing the change

[Xjinn]

bump
having a little slow RC syndrome, post shows but didnt update thread

[Glass World]

If anyone is following this, I spent most of last night building my prototype. It's 90% done and I've confirmed that all of the logic works. It wound up being a bit more expensive than I had hoped - I spent nearly $80 on parts (not including pumps or float switches), but I think that hopefully if enough people are interested it may be cheaper in bulk.

I've tried to make it as flexible as possible. Right now, to fully utilize the system you will need 9 float switches and 4 pumps (plus one more to mix the saltwater). This will allow for automated top offs and water changes as well as providing status of each of the reserviors with a tri-color LED (Full, Low, and Empty). It will allow you to push a button to refill the saltwater reservior and also have a backup high level and low level float switch in the sump to shut down the system if the water gets too high or too low.

A minimal configuration, however, requires only 2 float switches and three pumps (plus one to mix the saltwater). This will still allow for automated top offs and water changes, but you lose the reservior water level monitoring and the backup float switches. If you add an additional pump to this configuration you'll still have a push button to refill the saltwater reservior, however, instead of pushing a button and letting it automatically fill you'll need to hold down the button until it's full.

Finally, you can use pretty much any combination in between as well - with 4 float switches you can do the minimal configuration with the backup float switches. If your freshwater reservior is topped off automatically with a DI system then you don't need to monitor the water level in there, but you can still add two float switches to monitor the level in the saltwater reservior. If you just want a more simple full/empty status instead of full/low/empty then you only need one float switch for the reservior.

Hopefully I'll be able to finish my prototype in the next few days and then spend some time testing it.

[Glass World]

I need some more opinions of a few options I was thinking of adding -

As I was thinking about testing the unit I considered running the drain line to another reservior instead of to an actual drain. I don't plan to do this after I set up the system, but I was thinking that other's might want to use this configuration if they don't have a drain near their sump. If there is an interest in this, then I can add another option to monitor the water level in the drain reservior and stop the system if it gets full. Is this something people would have interest in?

Also, I originally designed the system to use pumps to move the water around, but it recently occured to me that if one were to place the reserviors above the sump, and if the sump is above the drain it would be possible to use solenoids instead of some of the pumps - instead of turning on a pump to drain the sump it would simply open a solenoid that would allow gravity to do the work. Is this something that people would like to see added to the unit? I wouldn't remove the ability to use pumps, I would simply add some additional contacts for solenoids.

Finally... anything else that I haven't thought of?

Thanks much,
Brett

[tang_man_montreal]

Sounds quite interesting indeed. I know many people (myself included) that don't have a drain near their sump. So this idea is good.

One issue about using solenoids is actually finding a solenoid that doesn't have copper INSIDE it. Even the Polypropelene ones from McMaster have copper inside.

[headhawg7]

Can you draw a diagram in detail Glass? I find it much easier to see how it works rather than read how it works and trying to picture it in my mind. I would greatly appreciate it and maybe a mod can post a sticky or put it in the RC diy section. Thanks for your hard work. Danny

[cwboomer]

for the ride

[H20ENG]

tang_man_montreal,
Which components of the poly solenoid are copper? I cant figure out why its even poly if they would use copper parts inside.
Thanks,
Chris

[tang_man_montreal]

Hi H20ENG,

Look at Zephrant's post down in this thread (page 3)...
You'll see what I'm talking about.

http://archive.reefcentral.com/forums/showthread.php?s=&threadid=140759&perpage=25&highlight=solenoid&pagenumber=3

[H20ENG]

Thanks T.M.M.
Forgot about that.
anyone found a decent one yet???

[JerseyReef]

Glass - Any updates?