Adding water volume with second remote sump

[Potatohead]

I have a 70g system which is mainly SPS. I am considering adding a Rubbermaid container of about 15-20g remotely where my ATO reservoir is, simply to add water volume to the system. I could drill a couple bulkheads in the container and use a 200 gph or so feed pump to feed it, and gravity drain it back to the sump. It would take some figuring out so as not to overflow my normal sump upon shutoff but I think I could pretty easily do it.

Is it really worth it though? Would it only be worth it if I could really add a lot more water, like 50g?

[AlSimmons]

If everything is doing ok now I wouldn't mess with it. (even if you could add 50 gallons more)

[Lavoisier]

I have to disagree as additional water volume adds to stability...more water means more consistent perimeters.

[matthemmings]

^agreed, there's probably a lot more useful things you can use it for like QT, hospital or a sin bin.

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[Potatohead]

I also feel additional water volume is better. I can't say I am having an issue now, but increasing volume increases the margin for error should something happen in the future.

My only real concern now is how to implement it. I was thinking about gravity drain but I don't want it to make any noise, I may have to run it as a siphon with a herbie style drain and an emergency. If the flow is slow enough it would be quiet but I wouldn't know that until it was setup. I'd rather do that as it wouldn't drain very much when power was shut off.

[ericarenee]

I agree that adding Water volume can increase stability.. But the Down side if If you have a issue and need to dilute your system for some reason you will have to do a much greater water change. Your water change sizes will increase your heaters will run more.. I think if you add additional water to add say A DSB Deep Sand Bed or Refugium its useful. but just to have more water in the System i see that the bennefit vs the extra effort if have a issue kinda wash out.. I have been there done that..

Just my thoughts.

[ca1ore]

I agree that adding Water volume can increase stability.. But the Down side if If you have a issue and need to dilute your system for some reason you will have to do a much greater water change. Your water change sizes will increase your heaters will run more.. I think if you add additional water to add say A DSB Deep Sand Bed or Refugium its useful. but just to have more water in the System i see that the bennefit vs the extra effort if have a issue kinda wash out.. I have been there done that..

Just my thoughts.

Completely agree. Additional stability is probably marginal, the things noted above are not.

[Potatohead]

Well, right now I am using a 10g tank for mixing, so I probably change 8-9 gallons which is still fine on say a 90g system. My bioload doesn't increase so I don't see a need to do anything with the skimmer or return pump or anything like that. I would likely just transfer the rock and Matrix I have in my current sump to the second one.

Maybe someone can help me with some math. I run my salinity at 1.0255 typically. My ATO typically adds about .25 - .30 gallons from activation to shutoff, which is just a little under .5% of my system volume. My old tank it was only about .2% because the return chamber was really small. Is .5% causing too much salinity swing? I have no idea.

Edit - Also depending on how dirty my filter sock is the level in my overflow varies about an inch, which probably adds another .25% variability also.

[Potatohead]

So I think I have this math right...

I calculate my ATO adds about 1/3 gallon or about 1200 ml each time it turns on. However depending on a few factors in the overflow/filter sock thing I figure absolute worst case is about 2000 ml, but that would likely be over an hour or two, not all at once. However let's do math based on worst case.

So;

70g/70.6g = 99.15%

This is the relationship between high and low volume points in the system.

34.5ppt x .9915 = 34.21ppt, or 1.026 vs 1.0258


Now if I added 20g to the system;


90g/90.6g = .9933

34.5 x .9933 = 34.27 or 1.026 vs... 1.0258

For fun, 50g;

120/120.6 = .995

34.5 x .995 = 34.33 or 1.026 vs 1.0259.


I truly thought it would be a much larger different than this. I think just with skimming and dosing and water changes it's going to vary by more than that just from those things.

[ca1ore]

Assuming the math is correct (not a criticism, just too lazy to do it myself), I believe you have your answer :)

[Reincarnate]

If everything in your tank is doing ok now then I just don't see the point of adding more water volume to the system. If it ain't broke don't fix it.

[Kevin Guthrie]

Sounds like you are already convinced but here's my 2 cents...

If you want stability, find a way to make it less complicated than what you already have. If you were talking about replacing what you have with a 100g stock tank I'd say go for it. But adding a sump is just more stuff to go wrong.

[Potatohead]

I'm sure you guys are right. I am trying to keep things relatively simple but that is just not really how my brain works, lol. I'm always trying to reinvent the wheel or second guessing myself trying to make things too perfect. I'll leave it alone.

Thanks