Water changes.. adding water then removing?

[KashAlp]

Hi,

Ok so heres the situation.. its time to do a water change in my tank, however i am having some issues with my return pump in the sump and i cannot shut it off. Its running fine now but there is a piece missing that makes it amost impossible to start back up without tearing the whole thing apart. Yes i have a replacement coming in a couple weeks..

anyways so i was wondering if there would be any harm in completly filling my sump with the new water and then draining out until the water level is where it should be.

Tank 125g
Sump 55g
Sump should hold about 25 gallons of new water from where i keep my normal water level.

[gweston]

I'd suspect that would work just fine.. as long as you have the capacity. You could even just do it in a few stages. Put in 50%. Let it circulate a while to distribute. Drain. Put in the remainder. Let it circulate a while.. drain.

[Fizz71]

Actually I would do kind of the opposite of gweston (sorry dude)...and it's actually what I do for ALL my water changes. I would add the water right at your return pump intake and take it out of your sump as you go. The reason being that you'll get as much old water out as you can while you're puting new water in. Otherwise some of the water you'll be removing will be the water you just put in. It's inevitable either way, but I figure get as much as you can out of it. You can also drain your sump to it's lowest possible point right before you do it too.

If you really aren't concerned with maximizing the water exchange, then just do it however you want...it's certainly not an issue to change water out live...it's just less effective.

[KashAlp]

Perfect. Exactly what i was thinking just wanted to double check. LOL lets just PREY TO GOD i dont have a sudden power failure while im filling my sump with new water. No check valves would sure make an aweful mess. lol perhaps i wont do it when its a thunder storm outside just incase

[Fizz71]

I don't suppose you have a bypass on your pump? You could just run "sumpless" for a while and do the water change in the tank.

[KafudaFish]

Maybe I am missing something because it has been a long week but I do not understand why you don’t do a WC as normal. If you remove water from the display or the sump the place the water is “gone” would be the sump because it is the lowest point of the system. As long as the return pump is submerged and running there would be no issue. You could turn your skimmer off so it does not flood. When finished, replace the water by adding to the sump or even the display if you wished. If you had an ATO, you could always throw that pump in your new water container and it would add the amount you removed.

[Fizz71]

Originally Posted by KafudaFish

Maybe I am missing something because it has been a long week but I do not understand why you don’t do a WC as normal. If you remove water from the display or the sump the place the water is “gone” would be the sump because it is the lowest point of the system. As long as the return pump is submerged and running there would be no issue. You could turn your skimmer off so it does not flood. When finished, replace the water by adding to the sump or even the display if you wished. If you had an ATO, you could always throw that pump in your new water container and it would add the amount you removed.

I guess I'm assuming it's because he is trying to change out far more water than he can drain at once without running the pump dry which IMO isn't a big deal for a short term, but his pump is obviously on it's "last propeller."

[KafudaFish]

Ok I can see that.

I fgiured he was saying that he was running around 30 gallons in the sump, would fill it to full, 55 gallons, and then start draining and stop once he got back to the normal level.

[KashAlp]

lol... yea my pump is on its last prop and i dont really want to run it dry. No i dont have a bypass either so thats outta the question.

If i drain from the tank b4 adding water to the sump then obviously the sump is going to run out of water after the water level drops below the overflow box and that willl cause my pump to run dry.

No worries though.. i will do my water change as posted above this week and hopefully a new pump comes in b4 its time to do another.

[KafudaFish]

How much water drains from the display to the sump when the power is off?

As long as the pump is submerged it will keep pumping and go above the overflow box and the water will keep moving.

I have a 95 with a 55 sump. I normally run 14 inches of water in my sump so I have 4 inches of clearance of "display water" that can drain back into the sump when the power goes out. My overflow is about 2 inches below the water surface. With the pump still running I can drain two inches of water from my dispaly because for me 1 inch of display height = 5.5 gallons.
If I removed 4 inches of water from the displace that would be 22 gallons removed from the system or 8 inches from the sump. My return pump is still submerged even though I have removed around 20% of the water volume.

[KashAlp]

the overflow box top is obviously right at the top of the water level so there is almost no clearance there. when i shut the pump off the water actually drains back to the sump in the return line.

sooo.. if i drain any water once so ever from the main tank with the pump still running the sump gets no refueling water. It will run dry in about 30 seconds with no water goin back into it.

im using bean animals overflow system.

[KafudaFish]

Why would it not get any refueling water? As long as there is more water in the sump than what you take out you will have some to keep the pump going and not burning it up. If the overflow top is right at the water level it only takes maybe a gallon or 2 to flow over right?

You run what 8 or 9 inches of water in your sump and your pump intake is 2 inches maybe?

So you could remove 15 - 20 gallons of water and still be good.

Even if a submerged pump is partially out of water as long as the intake is still wet the pump won't have an issue for that short of a time.

[KashAlp]

lol no man your confussed..

if the water level is BELOW the overflow in main tank where is the water suppose to come from to go back into th sump?

i can take out MAYBE 2 gallons before the water in the sump is below the return pump and its running dry.

maybe im explaining this wrong or maybe you just have something differant pictured in your head. Regardless i know how my system works because i made it and i cant do water changes by taking water out first before adding new water. Not with the pump runnning anyways.

Appreciate the help though

[KafudaFish]

Sorry I could not help more I guess I am really confussed on your system.

I was picturing a 55 gallon sump with 30 gallons of water in it becuase you said that you could pour in 25 and be ok. The return pump sat on the bottom of the sump like most and there was a "30 gallon reserve" being pumped back into the display. Even if you removed 20 gallons there was still enough water left over for the pump to pick it up and return it to the display. The display would fill and spill over the additional water into the overflow box and that water would then go into the sump. The process would continue until you were finished with a WC and had added back the additional water.

Though I did not help much:
1. Think about doing a by pass loop that dumps water back into your sump for things like this or for feeding.
2. Make a siphon hole in your return line that will prevent back flow if the power goes off.
3. Place the pump lower in case your ATO fails and the pump does not become exposed to the air since you said that right now if 2 gallons went it is running dry.

Good luck.

[Amp2020]

Put a ball valve inline on your return pump. The back pressure is not enough to do any harm. The pump will stay submerged and running the whole time. And there won't be any back syphoning through the return line. If your pump is seizing up every time it is shut off. It's time for a new impeller. If you let it run to the point that it vibrates a lot. Then the impeller will. Begin to damage the pumps inside housing and you'll have no choice but to replace the whole pump. Much cheaper to replace a $15 part than a $150 pump.

[Amp2020]

Or throw in a trash bag into the display tank and fill it with the new water then drain off the excess water till the sump level is right. Then drain the trash bag into the tank. Don't use the perfume smelling bags or anti bacterial or odor control bags.

[GTR]

On my 110 I used a 30g trash can with a bulkhead towards the top. I'd set a Mag drive in the sump that would pump water into the can. The can would overflow back into the sump. I'd let it run for about 15 minutes. Not the best use of freshly made water but it worked.

SteveU

[sdc19982002]

Why not just wait until your new pump arrives

[mihamlet]

Seems like it would work ok, although you would be removing less waste/detrious that way than if you remove the water first and then add in the fresh water. But it should work.

[Randy Holmes-Farley]

The effect is minor for normal sized changes.

If you remove 10% of the old water and then replace it, you effectively get a 10.0% change.

If you add 10% new water and then remove the same amount after complete mixing, you effectively get a 9.1% change.

So if that works for you, go for it.