Can we not simplify a fail-safe ATO? - The Planted Tank Forum
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post #1 of 18 (permalink) Old 04-10-2020, 03:40 PM Thread Starter
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Question Can we not simplify a fail-safe ATO?

For years I ran a dead simple gravity fed ATO - elevated RO reservoir, simple mechanical float valve. I took 5 seconds to clean and check it often. Went on vacations many times - never failed. Never worried. I know, I know and you're right, the horseshoe is uncomfortable.

Setting up a 90 again now after a long absence and seems everyone is tying themselves into a pretzel designing space shuttle fail-safes like your marriage depended on it. No comment.

If you can do gravity, why not this approach?

- elevated RO reservoir, fairly large, refilled by manually running RO system as required. Aerated.

- gravity line to basic primary float valve at tank
- fail safe - another identical line to identical float valve - inverted. Opens at never-exceed level.

- output of the fail-safe does not go into the tank but to a drain.

If the main valve sticks open somehow, water rises to your set max, opens the fail-save which drains the reservoir. Marriage intact

Pros: Dead simple, inexpensive, easy to maintain.
Cons (I suppose): Manually run your RO like once a month to refill. If the fail-safe is triggered, your reservoir is empty so no ATO until you get to it (but tank is full so you have a while). Gotta ensure the reservoir drain time is less than the tank max-to-overflow time. Not hard.

I realize all the cool kids want to play with pumps, solenoids and flux capacitors but it seems like crazy overkill for this simple function.

Thoughts? Is this heresy?

Persius
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post #2 of 18 (permalink) Old 04-10-2020, 05:23 PM
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Quote:
Originally Posted by Persius View Post

I realize all the cool kids want to play with pumps, solenoids and flux capacitors but it seems like crazy overkill for this simple function

Persius
I feel like in a lot of cases like displays having a storage tank/container above is not an option simply for looks. So tucking it below it goes. Sometimes may be simpler than running it to another room or attic or whatever to get it out of the picture.
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post #3 of 18 (permalink) Old 04-10-2020, 05:24 PM
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I had a similar setup on my 220 gallon reef tank for 10+ years. The main difference is my ATO fed into the 60-gallon sump below, and there was enough reservoir space in the sump to handle the 20 gallons of RO/DI in the ATO, just in case the float valve failed. It never did.
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post #4 of 18 (permalink) Old 04-10-2020, 06:00 PM Thread Starter
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Right, I don't plan on a sump and this setup does of course require the ability to have an elevated RO reservoir. I'm lucky - my tank is against a basement wall behind which is unfinished workshop space. All my gear, including a custom shelf for the reservoir goes back there out of sight and right beside a sink/drain. I've always tried to arrange my tanks like this whenever possible. Makes everything so much easier.

Just thought of one thing - how to buy/make/modify a float valve with 1/4" tube fittings on both in and out. Anyone familiar? I'm googling.....

Persius
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post #5 of 18 (permalink) Old 04-10-2020, 06:31 PM
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I run a 1/4" line to my sump and have a float valve. I also usually have an emergency emergency drain plumbed to a floor drain. They are pretty easy if you have a sump.

“Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.” -Jules Verne
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post #6 of 18 (permalink) Old 04-10-2020, 06:31 PM
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The Coralife float valve has 1/4" male NPT threads: https://www.marinedepot.com/coralife...-osmosis-units
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post #7 of 18 (permalink) Old 04-10-2020, 09:58 PM Thread Starter
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Same here Mark. Ran the same cheap float valve for must have been 20 years and 10 different setups. Had 3 huge oscars at one point that beat the crap out of everything just to piss me off. Various snail invasions as well. Plus I think I got it from a friend for free so it had even more mileage on it. Rock solid, never failed. I just gave it a once over and bounced the float a couple times when I did maintenance.

Is all this a solution looking for a problem? Where are all these jammed floats, ruined hardwood and failed marriages? Anyone have a good sense of how real this problem actually is? I may post another thread just for the ATO war stories. Or ghost stories? Lets see.

Persius
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post #8 of 18 (permalink) Old 04-10-2020, 10:40 PM
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The failures are more prone in saltwater setups, plenty of examples out there to google. Freshwater, I'd say there is so many factors in everyone's water quality, build up is inevitable for some, even if it wasn't for you or someone else. Some people are also lazier then others, some are on-top of obvious husbandry or preventative maintenance or just lucky.
Failures however do happen, and when it happens it can cost a lot of money. That is the concern, there is a actual risk percentage that may or may not happen. Not everyone is ok with wait to see mentality. If you rent or own a condo as example you have the costs of repair to other areas as well.
How does one weigh the risks, that is a personal decision with how acceptable you are of, risk.
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post #9 of 18 (permalink) Old 04-11-2020, 07:03 AM Thread Starter
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No question saltwater presents challenges that require a different risk assessment. I've been there. I should really have mentioned that its only freshwater I'm considering here. My bad.

I'm totally with you on the consequences of an ATO failure. Almost certainly its either bad or really bad. That's why this is interesting - we all know it must not happen. Ever. Its how we weigh (or distort) the risk and select what feels like the appropriate effort to avoid it that I think is oddly mis-calibrated.

First, my personal example of a single simple float valve fed from a reservoir by gravity, siphon or pump (if you must) makes my point. There's a great deal at stake, all depending on that one little $10 plastic device. Its so easy to point right there and declare it could never be trusted. Single point of failure. Too easy to imagine the snail, or leaf, or hard water scale, or any number of little things jamming those moving parts. Ok, but now spin that argument around. That mechanical simplicity is a strength. How many failure modes does it have? Two. If that. Lets just focus on those. Keep it clean and test it once in a while. Rig up a simple barrier to surface debris and/or tank life forms. Keep foliage away. Check there's no debris in the feed setup. None of this is remotely difficult and the resulting system is just not gonna fail, its not, over the spans of time between your regular, or random, mtc sessions.

Second, lets step back for a second. Why are we doing this ATO thing? For large tanks its absolutely justified. Go nuts. For less than say 120g (I chose that only because I've had several 120s and know the evap challenge during a dry Canadian winter) lets admit the ATO is simply a rather nice convenience. No pitchers or buckets, set and forget, steady water level and chemistry, more fun gear to setup and play with. But the true cost you bear is very high. It is the introduction, willingly, of this entire big scary flood anxiety. So, to address this new problem, we add more complexity, naturally. I'm saying hold on, try some healthy skepticism here. All that risk, all the cost, all the compounding complexity justifies a moment to rethink. The alternatives are many: simple robust float setup as above, or maybe rig your RO reservoir or setup so that its effortless to manually hit a switch or ball valve and stand there for 2 minutes. Or quickly easily fill a small jug and pour. It can be made trivial. Show the family. Set things up - design it - for the humans. You can usually find a few laying around.

If you're worried about those week(s) long vacations, many low tech low risk temporary setups can be made ranging from a fixed quantity drip feed to the valve arrangement above. You're gonna need a house sitter anyway. I assume you are here because you run a planted system. Then you well know they require regular attention.

I'm therefor suggesting that the value proposition of the "A" in "ATO" may often be far less than assumed and directed at an exaggerated problem.

Thoughts?

Persius







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Originally Posted by CrypticLifeStyle View Post
The failures are more prone in saltwater setups, plenty of examples out there to google. Freshwater, I'd say there is so many factors in everyone's water quality, build up is inevitable for some, even if it wasn't for you or someone else. Some people are also lazier then others, some are on-top of obvious husbandry or preventative maintenance or just lucky.
Failures however do happen, and when it happens it can cost a lot of money. That is the concern, there is a actual risk percentage that may or may not happen. Not everyone is ok with wait to see mentality. If you rent or own a condo as example you have the costs of repair to other areas as well.
How does one weigh the risks, that is a personal decision with how acceptable you are of, risk.
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post #10 of 18 (permalink) Old 04-11-2020, 08:40 AM
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I would never go back to a old style mechanical float valve when these days you can set up dual redundancy magnetic float switches, a dc solenoid valve and power supply for maybe $10 more than the mechanical float valve.
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post #11 of 18 (permalink) Old 04-11-2020, 12:35 PM
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Wait.....why aerate topoff water? It will amount to like 0.1% of your overall water volume per use.


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post #12 of 18 (permalink) Old 04-11-2020, 02:18 PM
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Quote:
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I would never go back to a old style mechanical float valve when these days you can set up dual redundancy magnetic float switches, a dc solenoid valve and power supply for maybe $10 more than the mechanical float valve.
You can set that up for $20? Can you share your setup?

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post #13 of 18 (permalink) Old 04-11-2020, 08:12 PM
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You can set that up for $20? Can you share your setup?

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Solenoid
[Ebay Link Removed]

Float switch
[Ebay Link Removed]


Add a 1amp 12v dc power supply to activate the solenoid.
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post #14 of 18 (permalink) Old 04-11-2020, 08:18 PM
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Solenoid

[Ebay Link Removed]



Float switch

[Ebay Link Removed]





Add a 1amp 12v dc power supply to activate the solenoid.
Heh, can you pm links or post Amazon?

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post #15 of 18 (permalink) Old 04-12-2020, 03:43 PM Thread Starter
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bpb - you're right but in general I don't like water to be stagnant for any length of time so aeration keeps it moving. Also, I have one reservoir that I use for both RO top off water and for water changes. Normally RO water feeds the ATO but for water changes I mix, treat, heat and aerate the change water in the same reservoir bin. I use a Python to clean the tank then refill with the prepared change water via a 1/2" pvc pipe to a ball valve at the tank. All gravity.

There's an airstone in the reservoir anyway, so I run it even with the RO water.

Persius



Quote:
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Wait.....why aerate topoff water? It will amount to like 0.1% of your overall water volume per use.

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