Controlling salinity

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Johan van Aardt

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so for my tank it is very difficult controlling salinity. I use a auto top-up but this is not accurate for the following reason/s.

1. i use a pipe as my overflow that is dialed back, this can make my sump fluctuate as the water in the pipe goes higher or lower.


This causes my ATU to go on even when its not necessarily needed.

I have googled a bit and you do get quite a bit of conductivity controllers(industrial) that could work.

Any idees guys?

@RiaanP @Hennie @leslie hempel
 
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johan, i will read up a little and offer comment asap.. im just in a little bit of a flat spin to be able to think it through thoroughly.. :)
 
RiaanP said:
please explain this part.
Click to expand...
it has a valve on it


Johan i understand what you mean, but the costs of controlling salinity that accurate cost more than its worth...

show us a pic of this system engine room and maybe we can tweak the setup
 
my enjin room, the chamber closest to the front on the right is the return chamber.

15174d90bc5de636b.jpg


The sump
15174d90bbaf8bb7e.jpg
 
the ATU is in which chamber now?
if you open the overflow valve all the way, it should be fine
water leaving is based on return pump flow anyway, unless your overflow sends to much water for your sump
 
1. i use a pipe as my overflow that is dialed back, this can make my sump fluctuate as the water in the pipe goes higher or lower.
Click to expand...

I must be honest i'm not following.
 
actually a 90mm pipe, if i open the valve completely tehe noise is hectic. wich is why i dial it back. unfortunately it is impossible to control the valve and make it exactly the same as the pump flow.

the ATU is in the last chamber were the pump is.
 
its difficult to suggest a solution when the problem is variable IE the fluctuation of the water level. only by sorting this out will you be able to make use of an ATU..
 
got a pic of the 90mm return, i might have an idea
 
Well, you could branch out from the plumbing after the big valve and then add a small valve / tap like I have. In my case the branching was done before the big valve. The small valve can be used to fine-tune the flow.
If you've used pvc weld glue on the pipes this might become bit of an issue.

About the ATU:
You will be paying an arm and maybe 2 legs for those sensors. You could use 2 normal float switches.
Place the one at the minimum water level where the ATU should turn on.
The second one should be at the max water level in the sump.
The lower switch is used to trigger a small circuit to turn on the pump.
When the water level reaches the higher switch, the circuit should turn off the pump.
Thus any fluctuations between the 2 switches should not trigger the pump. Only when water level drops below lowest switch, the ATU will kick in.

It's a bit finicky to get right at first, but it should work good. You can also add a 3rd switch just above the highest one that will cut power to the ATU pump incase the other switch fails.

Hope this helps / makes sense:)
 
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Johan van Aardt said:
my enjin room, the chamber closest to the front on the right is the return chamber.
42444dca4a31a5274.gif


http://www.marineaquariumsa.com/vbimghost.php?do=displayimg&imgid=37903

The sump
Click to expand...


Well, If i read correct, area marked 2 is return. it is not that a big sump, why dont you make the return smaller?

On my new sump, the return pump area is small, pump only fits barley, its deep... I used my ATU on this chamber, this is usually the first place you see the water level drop.

By using my float switch here, the moment evaporated water is to much, it runs the ATU.. has been working very well, I top-up about 5 liters a week by the looks of it. Salinity stays stable, havent had any problems.
 
i user 2 switches for my ATU, and both must be on for it to work, one floats updown like normal the other works in reverse, so that way both must be active to work and it eliminates waves turning it on

i will try and draw a diagram
 
i just want to see how its plumbed out the tank
 
15174d6ea51ebe64b.jpg


IMG_0084.JPG

its a normal 90mm bulkhead.

the return however also goes up in a pipe inside the 90 mm pipe.
 
OK, why not rather use a gate valve. A lot easier to set than a ball valve. Gate valve looks like a T piece. So you need to replace the elbow and the ball valve with one gate valve.
 
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