Water change % results?

[Daddyrawg]

If I do a 5% water change then 5 min later do another 5 % water change, will this result yield the same effectiveness as a 1 time 10% water change?

 

[MarkW64]

No, but close. It would equal a 9.75% water change. The problem is that when you do the second water change some (5%) of the water you remove is some of the new water you just put in during the first water change.

In the same way, if you do two 50% changes back to back they do not equal one 100% change. You would have only changed out 75% of the water.

 

[Tripod1404]

No. If you had 1000 balls and gave away 5% of it, you will have 950 balls. If you gave away another 5% from 950, you will have ~903 balls.

If you gave away 10% from the start, you will have 900 balls.

 

[Daddyrawg]

reason I say this is because I think it will be easier If I do the change from my sump but I dont want to turn off the return pump and I can only manage maybe 5-10 gallons before the water in sump gets to low and effects the pump running dry..

 

[feixjai]

Why don't you want to turn off the return?

 

[Daddyrawg]

Why don't you want to turn off the return?

If I turn off the retuen do I have to wrry about syphoning the overflow box again or no?

Just turn pump back on and i'm good?

 

[feixjai]

If I turn off the retuen do I have to wrry about syphoning the overflow box again or no?



Just turn pump back on and i'm good?

I don't have too much experience with overflows, with the exception of the DIY PVC overflows.

When I did have them they were able to self prime if the return were to shut off, as long as I didn't let air break the siphon.

I'm pretty sure most overflows will do that. Would be pretty catastrophic for all reefers if power went out or the return stops abruptly


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