How to automatic mixing water

[donlite]

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

[sphelps]

Originally Posted by donlite

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

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

[Kybol]

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

[golf nut]

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?

[asylumdown]

Originally Posted by sphelps

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

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?

[wolf_bluejay]

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.

[sphelps]

Originally Posted by asylumdown

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?

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.

[sphelps]

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

[golf nut]

Originally Posted by sphelps

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/

[mike31154]

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.