How to automatic mixing water
 

Well, i am thinking of a process to mixing my fresh salt water automatically so i can have auto waterchange.

I have salinity probe, float switch and outlet controls so i can turn on and off outlet when it meet the salinity. My only puzzle is how i can find some kind of rotating drum (just like a fish feeder), that can slowly pour the salt into the water bucket until it reach the salinity level. Anyone know one that is bigger enough to do the job?

you might also think of something with an auger, like the pellet stoves use. However, it would have to be made all out of plastic.

Auger seems to be the best option, and I can tell you because I've spent two years now looking at and for really well done automatic water change systems. There aren't a lot out there yet.

If you want some other ideas there have been people who have automated the process using their Reef Keeper controller on the Digitial Aquatics forum. Even if you don't have an RKE, some of the styles and problem solving techniques might be worth it for you.

*Edit* While I was looking for something else this thread on RC popped up about different mixing stations. I know they aren't all automated or anything, but it might give you some more ideas. Salt Water Mixing Stations Let's See Them

Rotating Drum
 

Rotating drums immediately brings to my bunny mind a Lapidary tool.
:laluot_23:
Lapidary is the art of cutting rough rock into gem stones. Normally, rotating/grinding machines are used for the process.

A less-formal method involves using various sizes of rotating, plastic-lined, drums for polishing rock.... it's a good method for teaching kids how to polish semi-precious gems since the machines are much safer.

Drums can range from one pound capacity to any size you want (i.e. 10, 20, and commercial sizes beyond that).

The trick will be to automate how the salt is dispersed.

I suggest speaking with the Calgary Rock and Lapidary Club. They could direct you to people who could help you see these units in operation and even to buy a machine if someone is no longer using theirs... Here's the link: http://www.crlc.ca/index.htm

Hope this helps and will look forward to hearing your success :-)

Bunny

The issue with drums is finding a food safe drum so that the Bearings aren't exposed to the salt, and also made of stainless. Anything else would be pretty scary to use on the tank :S.

My opinion would be a simple hopper with a valve. You need something that will seal off the salt when not in use, if it's in the same area as mixing water, the humidity will make it a salt block in no time. If you made a desenct sized hopper with a small outlet, even a 0.5" opening you could open/close that to add salt. Program it so that the hopper is open for a short period then closed for 20+ seconds to allow the salt to mix. Make it cycle whilever your salinity is low.

Sporadic Hopper units make sense..... brainstorming fwiw :-)
 

All very valid points...

With that in mind, Lapidary tumbler drums are typically isolated from bearings... I wish I could comment on the grade of the poly/vinyl liners but I've never tested the units for SW applications.

There are a number of manufacturers worth speaking with i.e. Thumlers, Covington or Lortone (just don't look at the cheap units - they are trash and don't last.)

Covington does make a "Hopper-type" unit for polishing gold/silver castings... Here's a link to see what they look like...
http://www.covington-engineering.com/deluxe_tumblers.htm

One might look at their "Vibratory" Tumblers as well? Tho I'd be concerned about heavier elements sinking to bottom and causing tank troubles... http://www.covington-engineering.com/vibrating_tumbler.htm

I'd personally lean towards Covington for getting answers to technical questions...

I do like your thoughts on using a hopper sporadically :-)

Bunny

Super saturation is your answer. Setup another water top off using something like a 29 gallon aquarium. Drill and install an overflow in the aquarium and mount the aquarium above sump level. From your fresh water top off use another pump or solenoid depending how it is setup. Send one fresh water line directly to the sump (Fresh top off). Send the other fresh water line to the 29 gallon aquarium (salt water top off). Plumb the overflow into the sump so when fresh water is added to the 29 gallon it overflows and drains into the sump. Next fill the 29 gallon with water and add a full bucket of salt, use a small powerhead to keep the water circulating and even a heater if you wish. Now setup your controller to either activate the fresh water or saltwater top off based on the salinity measurement in the sump. The salt water added will be supersaturated but it won’t matter as the controller will simply cut it off once salinity is restored in the sump. This will maintain salinity so to auto change water simply hock up a pump and timer in your sump to pump water to a drain. Depending on the controller you can even set an alarm for low salinity which will prevent the pump from removing water so it won’t change water if salt is needed. And when salt is needed simply add another bucket to the tank, doesn’t get any easier. Done this exact system with a profilux before, it was dope!

I may have an idea for you , I own a convenience store & I have a hot chocolate machine that has a food grade plastic hopper with a plastic auger in the bottom . It is driven from the back by an electiric motor & coupler system. the hopper would probably hold about 2-3 lbs of salt at a time . I will try to post a picture for you if interested.

Problem with supersaturated solution idea is the amount of maintenance you have to do to the ATO pump. As It doesn't run continously so if the water evaporates your ATO will eventually clog with salt pretty fast since it is supersaturated.
I'd go with the auger idea, just what type of material it should be made of would be the issue, plastic wouldn't work as the salt would act like a sandpaper and would wear the auger out in no time.

Though I wonder if an auger made out of PVC material would work.

I do like the supersaturated method but was warned against it for some reason when I posed a similar question, I will need to dig up the thread that is out there someplace.

A plastic auger wouldn't be that hard to manufacture, what size do you want?

Here are a couple of pics of the hopper I was talking about . Not great but I think you can get the idea.[IMG][IMG][IMG][IMG]http://i966.photobucket.com/albums/a...9/P1050144.jpg[/IMG][/IMG][/IMG][/IMG]

Thanks russp, but I am looking for something that i can just buy because i am not that handy man that can make things :-) SAD

Actually the way I described it this could not happen. The salt water top off pump will only pump fresh water into a tank and then the saturated salt water overflows into a drain that goes to the sump. If you made the drain at least 1/2" there's no way it would clog, plus it's a drain and will be empty unless the top off is running.

Like I said this system was used on a reef tank for about a year before the entire system was sold off. No problems occurred during this time. A hopper system isn't really going to work as well as one might hope, it will cost more and can clog up if the salt is exposed to air. Ever left your salt bucket lid off before and ended up with salt bricks? Same deal. Even straight out of the box or bucket salt is often clumpy.

I think we've discussed this before and I remember my concern being related to whether the levels of elements would be affected in the saturated salt water. I did monitor the measurable levels in the aquarium which had this system and for the most part they remained stable. The tank didn't have any dosing or supplemental systems so the levels weren't always perfect but did remain within reasonable tolerances. Basically I didn't notice any difference in stability before and after the system was installed.

water
 

This is a little of base but I am looking at having 2- 20 gallon plastic containers one with fresh water and one with high concentration of salt. When water evaporation is detected it acts as a auto top off system filling it with fresh water. When it needs a small water change using 2 salinity meters one in the tank and one detecting the water being mixed it can perform water changes. The system is not that simple but at the same time there is parts that you can purchase from robotic sites that are cheap and easy to hook up to your lap top. Let me know if this already exists and what you think, Don:idea:

You don't need two salinity measurements, only one in the tank is all that is needed.

what about something like this? I used one before and though maybe something along these lines would work?http://www.grasshoppercontrol.com/model62..html

You obviously wouldnt need the engine or blower. The hopper is all plastic, with a electric plastic auger running along the botton, with a gate valve type thing to control the rate into the fan.

Cant find a better pic though, sorry

I saw this one yesterday. Don't know how good it is but might be worth a look. http://www.genesisreefsystems.com/categories.php?cat=7

This was the original thread on RC when I asked the question.

http://www.reefcentral.com/forums/sh....php?t=1623983

I really have no idea how a bucket of salt is produced, but if it all has to be mixed to get all the additives then I can see that being a problem, if one ordered a particular color of paint which came in paint ball size pellets and had to be mixed totally I can see that if a single pellet of black wasn't mixed with the rest of the tub and small portions were mixed frequently then one of the batches of paint is going to be very different.

If however the components in the bucket are a multiple of tiny amounts mixing short batches shouldn't be a problem.

This begs the question, is it OK to split a pail of salt with your friend?

I hope I've followed your original description of this system properly, but it sounds like you will first pump in a bunch of fresh water to the sump, and then gradually return the water to the correct salinity using the super saturated solution. Is that right?

would that kill stuff living on live rock you have in the sump?

What about a more cartridge like system
 

The original idea about this came from a sampling system for ocean water at different depth -- so pardon me if the idea sounds half baked.


Why bother with a hopper or motor controlled device that can cause problems -- why not have multiple "drops" of measured salt.

In the most simple but costly version: have 5-10 pvc tubes sealed on top with a flapper on the bottom controlled by a small motor each. Into each one goes to correct amount of salt for the mixing tank and all are placed above the tank. For a batch of salt, add water, open 1 tube, mix and serve.

On the cheap you could do a circle of tubes with flappers and a disk on the bottom with 1 hole in it. rotate disk a little and 1 tube opens through the hole.

A little less automatic for a whole bucket of salt, but would work well for 5,10,20 batches that you could measure out all at once and forget it.

Pretty much, when water is removed from the sump the controller will continuously switch between fresh water and saturated salt water top offs to control salinity with the aquarium until the sump water level is restored. The top off flow rates are typically pretty low compared to the sump turnover rate so there should never be any large spikes of high or low salinity to affect anything in the sump or display. There's really no difference between this and a regular top off. A regular fresh water top off adds fresh water directly to the sump and it doesn't effect anything. Adding the saturated salt water will be the same.

You should however have the two water inputs upstream in the sump from the salinity probe otherwise the reaction time for adjustment may be too slow and you'll end up with a bigger range in salinity.

Also so if anyone else is interested in another alternative to auto water change without a salinity probe you could setup something like this:

• Two separate top offs will be needed, one for fresh and one for salt.
• The fresh water top off is simply just your standard fresh water top off, set the float switch to trigger at your desired sump level. The only difference is you want the fresh water to be added slowly so use a small pump or restricted pressure/gravity feed.
• The saltwater top off will require a decent size storage tank where you can store premixed saltwater (the same salinity as the display). Install a separate float for the saltwater top off slightly lower than the fresh water float. Just low enough so the saltwater float isn’t triggered from evaporation.
• The saltwater top off should have a fast flow rate so use a decent sized pump.
• Next install another decent sized pump in the sump to remove water quickly for water changes. You can use a timer to activate it or just a switch if you prefer to keep more manual control over the system.

That’s pretty much it. The fresh water top off will replace evaporated water, the slower flow rate will keep up evaporation since this is a slow process. When the pump in the sump is activated to remove water it will do so quickly and activate the lower float switch which will trigger the salt top off. Since the fresh water flow rate is slow the fast saltwater flow rate will top off removed water before much fresh water is added. To make up for the small amount of extra fresh water added during a water change to can keep your salinity a little higher in your make up container. How much higher will depend on your setup and may require a little experimenting.

To limit the size of the container you need for saltwater storage you can try using saturated salt water. You will have to experiment but by placing the saltwater float lower in the sump you can control how much saturated solution is added in comparison to fresh water. You will however have to maintain a constant salinity in the make up container. You can either maintain a high salinity by measuring or you can maintain maximum saturation by keeping temperature consistent and always making sure some salt remains undissolved

Curious as to why you leave some undissolved?

I agree that supersaturation is the solution to an economical top off design but a number of questions have been raised and it would be interesting to understand how many of the questions are valid, usually we mix batches of salt well ahead of when we do changes, some say this is needed to allow all chemicals to mix thoroughly,can we take a cup of salt, mix and serve immediately with no adverse effects?


Liquid handling isn't rocket science, I use proportionalizer valves every day and they work fine, precipitation is another issue in premixes as I am told, which could lead to other problems, removing a known amount daily and replacing the same volume appears to be less constructive as doing larger batches fewer times... true false?

speaking of liquid handling.......http://www.wimp.com/beerscup/

Automation can be a good thing, but for mixing your salt water? Come on, such a simple task and we try to complicate it by coming up with some ingenious, but quite technical and work intensive/costly ideas. How long does it take to measure some salt, toss it into your mixing container and give it a stir or start up a powerhead? Augers, valves, proportionizers..... egad. The maintenance of all the extra gear sounds like more work to me than just doing it manually. Apologies if I sound a little negative here, not really my intent, just trying to present the simpler point of view.

I just use the highly advanced method of drawing a line inside a bucket, filling the water to the line and writing on the outside of the bucket how much salt is required to bring that volume of water to the desired salinity. Works every time and takes about 30 seconds a week to make up my water change water. No extra cost or maintenance. Nothing at all wrong with mechanizing things but its up to the individual to determine if it is really saving any time or effort.

Do you have a rotary phone?

Seen one for sale lately?

Ensuring some salt always remains undissolved insures the salt solution is at max saturation and with constant temperature you can be sure the the salinity of the make up is consistent (max saturation at given temp). You could also in theory measure the salinity and keep it constant however it can be difficult to measure salinity of saturated saltwater and it's easier to just simply look for undissolved salt. It makes other options easier to employ as well. This is of course only important without the use of controllers, a controller eliminates the need to maintain constant salinity in make up water.

Some salts seem to require longer mixing times but I've used many salts that mix clear almost immediately and I've added cups of salt directly to sumps many times while preforming water changes without any adverse effects. Other peoples results may vary but I've never really pre-mixed saltwater ahead more than a few hours or so, typically I mix new water at the same time as I'm removing old water.

In the automated systems I've used and setup in the past I've always put importance on the less more often approach for stability. The systems would usually change a smaller percentage daily rather than a larger amount weekly or even monthly. This could very well be an important part of the systems I've previously described.

Takes even less effort to top off your tank with fresh water compared to changing actual saltwater but most would agree a standard ATO is a must have these days. Not only to make your life easier but to promote stability. AWC is a very simple concept with a programmable controller with salinity measurement and employing a such a system is just another way to promote stability and free your time for more important things like actually enjoying your tank. If you enjoy manually mixing and changing water that's cool but most would agree it can sometimes be a hassle and often gets neglected.

water changes
 

What I have set at this point is very simple. I have 2- 30 Gallon drums (coke sells used drums for about $20). One is filled with fresh water and is connected to a float switch in my sump. The other tank has saltwater in it. I use one water lifting pump for the top off and 2 pumps for the water change. The water change pumps turn on and off together throughout the day. The problem is that the 2 pumps must have the same flow rate. I checked them and they are almost the same. I also have a second float switch that turns all the pumps off if something stays on or off. It is not a perfect system but it seems to work.:idea:

Yeap a very common method and works well for many people. With almost any system you'll still need to check salinity and make adjustments. Even systems with conductivity probes I still found the calibration/set points required slight adjustment every few weeks.

Rather than matching two pumps I find the use of float switches to remove and replace a consistent amount of water takes a lot of the guess work out.

Would a double stage cylinder be a better choice if it could be produced inexpensively?what volume would you need to move?

The chemist in me really really cringed at this. Saturating the salt water mix is bad idea.
This would work IF we were only using one salt, but the mix is just that, a mix. All the different chemicals that make up our fairly expensive salt do not saturate at the same levels.
This saturation is used sometimes to purify (removed unwanted salts) in many production chemicals. The NaCl would be almost the highest solubility. So you end up with just mostly NaCl and almost all the calcium and trace minerals would be what would precipitate out of solution.


Think of it this way -- if you dumped a whole lot of salt mix and pushed it to saturation, separated the precipitate out, add more salt mix and repeat -- you would have some expensive NaCl without much else in it.

So how would you make a good solution that could be handled ?

This is a real question, I respect your expertise, what would be a better method?

Sorry for the delay in responding -- been away a few days again :)

If you want to get really, really particular you could look up the solubility of each "ingredient" in the mix, and from the ration in the mix figure out how dense you could go.
Off the top of my head, I would be that it would be the calcium. as it is already super saturated in NSW anyways (magnesium is what allows this). As you start pushing the salinity to 2 or 3 times the normal amount, you could expect to see calcium precipitate out onto pump, glass, and everything in the super saturated hold tank. It will also push the equilibrium of the carbonate and probably cause issues with the buffering ("chalk" precipitate)

If you have a calcium reactor, or some cheap way of replacing the calcium you should be OK as most of the stuff in there does have a high solubility. Just always expect your salt mix to be very low in calcium and add as needed. If you are buying the super expensive salt with NSW levels of calcium, they you are wasting a lot of cash. IO salt is typically low on calcium and low in magnesium as well.

The best way, would be to not over saturate your salt as I'm not sure what else would go a little out of whack.

I'm almost thinking that the easiest and best way of doing this, is to just mix up a ridiculous amount of salt water at a time and do the "2 balanced pumps" to handle the water change -- mostly because I do add magnesium, some buffer, and calcium to get my cheap salt up to par and this might be easier with a larger volume of water. IE: 200 gal salt water storage in the basement and just change a few gal a day.
I don't think the salinity could get to out, and with a controller, you could just add some salt water instead of fresh to raise, or pump out a bit and add fresh to lower the salinity...... This way, you wouldn't really care what the salinity in the storage tank was (high or low) and let the controller work it out for you.

Yes this was my original concern with the method as well. However as mentioned I tested it long term on a reef tank with good success. I did not experience any precipitate and the levels in the display remained as consistent as the previous method of manually mixing and changing water.

When you think about it, it's no better or worse than how water is traditionally changed. Most people don't mix a full bucket of salt at once to insure optimal levels. Instead they grab a few scopes here and there which can result in different levels each time.

Not sure what you mean, can you explain? There is of course is a ton of different methods to remove and replace a consistent amount of water, I just mentioned one that I've used before.