Auto Water change through skimmer questions

Not necessarily, a month or so ago, I had my controller froze up and everything got stuck on! Luckily I was there and noticed though, however, it could have been disastrous if I was away....

I guess you just need to decide if the float switch adds anything over just having it flow back? I'm never thrilled when a skimmer overflows back into the sump, but it happens now and again, seemingly without issue. It's the same thing really, the bucket is just like a bigger skimmer collection cup. You could have the float switch to e-mail you certainly. In the end it's an personal opinion as to how important it is to turn it on and off.

Peristaltic dosing pumps generate a ton of head pressure, so I doubt it. (Edit: the aqualift does not generate a ton of head pressure, so, it may, if not filtered well). Especially if you put filter sponge on the end of the tube to keep the bigh stuff out.

 

My whole system would likely melt.. That would be TERRIBLE... Even with fallback settings to OFF? (If this was to happen, I would have much bigger issues than this auto water change system still running..)

I guess that's true.. If it flows back into the sump anyhow.. It really doesn't matter if the skimmer keeps going or not. I'll play with both and see what I like the best.

Hmm.. I may end up just getting another BRS 50ML pump to empty it... I'll experiment with it. This part isn't that big of a deal. At first I'll manually dump it if need be.

 

I think the only thing I had set to default=off was my lights. They were on, the time was frozen though, so don't know if it would have gone off if the time was still working... I really only use my controller to turn things off if they malfunction, for example my heater, or for non-critical things like alternating powerheads. Now my lights are on good old fashioned mechanical timers though


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What kind of controller are you using?

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RKL. The Apex should be better I think.


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The more I think about it.. I may just dose the salt evenly throughout the day.. and just use the salinity meter as a guide to help me manually control how much is put in . This will force me to stay on top of it more, and will take away another failure point. This will only work if the skimmer is relatively consistent. (Which really, the whole project depends on anyhow)

At this point.. It's really pretty redundant... No more than 5g can come out. So that's problem number one. And the salt going in the tank is now at a controlled point. So at least the worst case scenario now is that 3g(or I guess the entire 30g if the outlet gets stuck on... whatever) of additional salt water is added to the system and none removed. That's if the skimmer pulls nothing out and the pump keeps pumping.

 

I think you are making this way too complicated and way too many points to fail. Notification is not prevention.

Many use automated water changes and so did I. Using your skimmer is very inconsistent because skimmer performance can be impacted by a number of things. You are pulling out some guess of a number over some period of time all the while evaporation is taking place and then using a conductivity probe to put in some undetermined amount of water to reach some salinity point that is going to be very stable and show change slowly. If disaster did strike you would be hard pressed to even find a true failure point. While many things are "possible" in reef keeping, if it is not practical, then it is a crash waiting to happen... not even going to go into the endless water supply of your RO/DI hooked straight up to your tank.

First, it is not a very good way to run a skimmer.... basically we can only do so much... skimmer don't remove DOCs, they remove hydrophobic DOCs. Plenty of soluble DOCS floating around. All mechanical filter benefit from a "seasoning" of the media... well obviously there is no media in a skimmer, but it is a mechanical filter and it does work best with a constant foam head. By using your skimmer to remove water you are not building up that head for other organics to get caught up in and removed.... however, if a organic is bound up in the skimmer it is effectively removed from the system. I can't really prove that your skimmer is more or less efficient at doing it's job, but it would seem to me it would be less. I just alway have been of the though that you use the right tool for the job... that you spent a few hundred dollars on a bubble machine to remove waste and you should probably run it best to optimize that job. you can buy a $12 power head to move water.

One problem with the skimmer is that your replacement is set by the dosing pump, but that skimmer production can increase or decrease... if your skimmer increases removal and it is more than your dosing pump then your ATO will kick on and top off with RO/DI. Too many non related additions and subtractions going on. If your skimmate production drops off for some reason, then you will continue to dose salt water... then you will not top off, and you will continue to evaporate which will increase salinity more.

The only way to do fail safe automated water changes is to automate taking out a set amount and then putting it back. You can use a conductivity probe as back up to monitor, but I would not trust automated operations to a conductivity probe.

I used a Tunze Osmolator ATO with about $40 in extra parts ran by my Apex or a completely failsafe operation. You could also get the same results using float switches or any ATO I suppose, but I am partial to the Tunze.

The other way is to use a dual diaphragm peristaltic pump. They can be had, but are sort of expensive... $400. That is relative since $400 is not that much in this hobby.

I did a lot of talking to a guy that was trying to automate his salt water production... it is much much more complicated than it sounds. I realize you are not trying to do that, just saying that he was having a heck of a time actually making a set solution using conductivity probes. It was an interesting discussion.

I would be more than happy to give you my thread on my auto water change, there is some good info and discussion. I am all for automated changes, but it needs to be much much simpler. Once I got mine up and running, I had no worries, but I also did the changing of the RO/DI and the salt water.... so the chore of the change was done, but I was still on top of changing bottles and my reservoirs where of such size that nothing catastrophic was going to happen if anything failed one way or the other.

And my last little wrench I'll throw in.. I question how much water you need to change in the first place... that's the point of a good skimmer, throwing a turf scrubber in to boot and I would be doing none.

 

I really appreciate your post and would love to see your thread.

We addressed every single one of those issues throughout the course of this thread. Give me a second and I'll post a recap of the decisions made throughout the thread.


After talking to the guys at coralvue at length. I am confident I will lose 0 efficiency on the skimmer, I also don't really think I'll gain that much skimmer efficiency by skimming wet. But this allows a slow removal of water and doesn't add any equipment, both nice bonuses.

 

So here is the original thread that I learned about this from.

Easy Tunze Ozmolator based Auto Water Change system - Reef Central Online Community

Here is my thread

http://www.3reef.com/forums/i-made/my-tunze-osmaolator-automated-water-change-89115.html

If you do not use a Tunze ATO, then the principle would be the same... use a relay to turn off your ATO makeup pump and turn on a salt water pump... get rid of water, top off using salt water, deenergize relay and go back to ATO operation.The Tunze has a very small window and keeps level withing 1/8" of an inch, but I know others do too.

since you have a conductivity probe then you would be able to monitor salinity.... there may be slight variations between salt water make up and what is in the tank... you could still skim wet, and if you use two part dosing like me, you might see a slight up tick in salinity anyway over time.... (which I never saw)

but how you would automate that with a conductivity probe is that say you want to keep 1.026.... then at 1.027 you simply tell Apex to not turn on your salt water pump... the water change would occur... no salt water added... ATO back on... top off with RO/DI.... same in reverse... at 1.025 tell relay to energize.... ATO functions like normal.. but you top off with salt water

... point being is that if you only change out 1-2 gallons (or more but it is relative to your system volume, a very small amount) a day and then top off what you are loosing with RO/DI or salt.... changes in a salinity happen over a much longer time and much slower, it might take 2-3 days to move salinity.... the problem comes in how fine of a point you can use with Apex... I know temp needs to be .3 degrees... but I don't know what the historisis is for the conductivity probe and how fine you can set it.... I personally would want say... on at 1.025 off at 1.0255 same for top end of 1.0265 and 1.027... to keep a window of 1.0255 -1.0265 but I don't know if that can be set that way.

I thought you could set it up using ppm so if you used 35ppm... then I think using 34 or 34.5 would be possible and still give a decent range.

But just to be clear, I did not want to use a conductivity probe to "maintain" salinity... I only thought I might in the future... since you have the system setup, it is all there and ready.... but I would use a probe to correct gross changes.... something out of wack... I kept my salinity pretty stable anyway, very tight, and that a conductivity probe would just be another level of security since the stuff is there.

You would still be able to monitor outlets and see what was energized and readings and what should be energized and history... so no surprises if you keep up anyway.

 

Here is my plan.

Skimmer is plumbed to a 5gallon bucket with a bulkhead drilled at the 4 gallon mark or so that will dump any excess back into the sump. Giving me a hard 4gallon maximum before any else leaves and I have to make a decision (to remotely empty the bucket) The float switch at 2.5 gallons will warn me that the bucket is full and from there I can decide to activate the pump to dump the bucket to outside, or I can cut the skimmer off if I feel there is a problem (IE the bucket filled way faster than it should have)

The skimmer will be tuned to pull 2.5 or so gallons a day out and the salt pump will be programmed to dose 2.5 gallons a day back in (or the mathematical equivalent if I use water mixed to a higher salinity, which I plan too). The conductivity probe will only be used to monitor the salinity levels rather than as a decision maker. The ATO is unaffected by all this.

The biggest down side is I will need to tweak the salt pump each day to compensate for inconsistencies in the skimmer. But that's really not a big deal as we are talking small numbers on a big tank. This set up means that at most, I will have an additional 1.5 gallons of saltwater replaced with fresh water... Not a big deal at all on a system my size.