Too many water changes?

[chevyjaxon]

Just wondering if theres a such thing as too many small water changes in a week? my system is currently around 170 gallons. I change about 7 gallons a day.

[Aquattro]

I'd say that's not doing a whole lot of good, as each tiny water change per day is diluting the good water from the day before. The nutrient dilution in this schedule is likely non-existent. You'd be much better changing 50g once per week.

[Myka]

There is no such thing as too many waterchanges, but there is such a thing as inefficient waterchanges. Your waterchanges are inefficient. On your waterchange tomorrow you are removing part of that 7 gallons you did today, that is not efficient. for example, you would be MUCH better off doing 49 gallons (7 gallons times 7 days) once per week. In this fashion, ALL 49 gallons removed would be "old" water.

Really though, 10-20% per week is usually quite sufficient for most reef tanks (assuming this is a reef because it is in the reef forums), and most of the time little benefit is seen by increasing the amount changed per week.

[Myka]

Great minds think alike Brad!

[chevyjaxon]

Interesting, I figured in the never ending battle against too many nutrients on a reef, and in the struggle for keeping parameters the same without any swings in water quality (one way or the other) a small amount each day would be better with the weekly total being instead of 20% now 30%. I just dont want any big nutrient swings in my system.

[reefwars]

Originally Posted by chevyjaxon

Interesting, I figured in the never ending battle against too many nutrients on a reef, and in the struggle for keeping parameters the same without any swings in water quality (one way or the other) a small amount each day would be better with the weekly total being instead of 20% now 30%. I just dont want any big nutrient swings in my system.

if your consistent on your water changes nutrient swings wont be an issue as far as nitrates and phosphates are concerned.

[Myka]

Originally Posted by chevyjaxon

I just dont want any big nutrient swings in my system.

Test PO4 and NO3 minutes before a waterchange and then also 3 or 4 hours after a waterchange. Try this with a 7-gallon waterchange, and then try it with a 25% waterchange. You will find the numbers just before a waterchange and the numbers a few hours after a waterchange will be very similar to each other despite the size of the waterchange.

Waterchanges do little to reduce nutrients unless they are very big, and very often. Such as daily 50% waterchanges which I wouldn't recommend. Instead of thinking of waterchanges removing stuff, think of waterchanges as replenishing stuff.

[chevyjaxon]

yes replenishment! I have run a successful fowlr tank for 5 years, got rid of what I could, then put it through 6 months of darkness.....
I am restarting it as a reef and being very selective what I put in. I understand replenishment is the secret to sucess. guess ill be putting less effort into daily waterchanges and more effort in once a week to a big one.

[Money pit]

OK so lets do a bit of math. The tank is 170g, a 7g water change is just over 4%. So tomorrow when you do your next 4% w/c, all things being equal, 4% of your w/c will be water from yesterday. 4% of 7g is a bit over 1/4 g. I don't see that as inefficient, more as not as efficient. But efficiency isn't everything. If you find daily 7g w/c to be a routine that suits you, or more manageable than weekly 10-20% changes, then from a workability point of view, this is the way to go. If both methods can be done, then do the testing that was mentioned. Of course, if you test before and after a 4% change the drop will be much smaller then after a 10-20 % this only stands to reason. To keep things on a level playing field, you would need to test after a week.
Myself I tried 2g daily w/c in a 40g with about 15g in the sump, the tank looked great, but I found it unsustainable. More to the point, I would forget to do them. I found it much easier to do the daily changes, but couldn't get into the routine. For me weekly w/c are the way to go.