Water Changes And Acceptable Water Parameters

[jeasko]

Only reason I'm writing this post is there seems to be alot of different information arround water changes and what percentage and how often it should be done, this came around as I was talking to my reputable LFS and they say 25 percent every 2 weeks (as corals dont always like frequent water changes) then someone else says 10 percent every week (this is what I do and it seems to work) so is there a difinitive answer or do we all do things differently with the same results.

second part of this post is likely to open up a whole can of worms around acceptable water parameters as I Have been asking a few questions around these in the past else where with no clear outcome

the guidlines i try and follow is as follows

PH 8.3

KH 9-13

Nitrite 0

Nitrate 0

Calcium 400

Phosphate 0

ammonia 0

temp 78-80 deg F

While these are all ideal parameters what are the acceptable upper and lower levels? as its not always possible to keep to exact figures i thought id see what people see as an exceptable variation

Look forward to your responses

 

[jeasko]

No one got any input on this one then?

 

[dilbert]

I am doing 10% water changes every week, but mainly to add trace elements like iodine and strontium in a simple and easy manner as it is diificult to measure those and adjust the right amount with expensive supplements.

If there wouldn't be that fresh salt issue I would presumably do it less often. I got also a clean little tank with not many life in it, so it depends much on the size of the tank, its structure and its livestock.

The same counts for those water parameters. My weakest links are the shrimp and maybe the snail. As most people don't do any experiments with their animals they only get some figures that are common and try to stay below of them. The weakest link also determines always the overall maximum figure so I doubt that many people will come up or forward with some reliable max or min figures.

Then, posting max figures is often discouraged as negligent people would get a boost from those figures to be even more negligent.

 

[andywg]

It's all a matter of balance and depends on each individual tank as well as the aims of the tank.

A FOWLR pred tank can hit 40 and 80ppm nitrate with little problems, and calcium and KH are almost of no concern, whereas they will be closely monitored in an SPS farm.

Water changes will depend on the stocking and filtration of the tank.

 

[jeasko]

Dilbert thanks for your reply, what im trying to find out i guess is mostly to do with nitrite and nitrate as some people will say the nitrite at 0.05ppm is not harmful but you should take steps to reduce it asap and some say its no prob to run the tank as long as it stays under 0.1ppm for me itry and keep it at 0 and if i see a rise to 0.05ppm i take steps.
However there are a few different opinions on nitrate as some say upto 50ppm is acceptable (live stock specific i know) some say 30ppm is where you should be taking action and some say 40ppm is the worrying point.

IN NO WAY AM I SAYING YOU SHOULD BE CARELESS WITH YOU WATER PARAMETERS

what I am trying to find out is at what point we should be taking steps to get our values bak to where they should be.

FOR EXAMPLEmy nitrate is at 20ppm (due a water change over weekend)which while there is no great concern with this I have checked for ammonia and nitrite to check the are both at 0 to satisfy myself there are no greater probs, however if i had a reading of 40ppm i would take action asap to try and reduce this, which is i guess what I am looking for guidance for to check my logic is correct and that my values to be concerned at are in the right region. similarly if my KH gets lower than 8 (6 being a concern of a KH crash) i would take steps to raise it

 

[Lynden]

Remember that doing a 25% water change biweekly will be more efficient than doing a 10% weekly water change, at least that's what I have been led to believe. Think: "Is there more water in the wine or more wine in the water"?

 

[jeasko]

lynden not sure but if the wine tastes good who's worried

this is exactly the sort of thing im talking about, some people say do a bigger water change less frequently and some say do a small water change more frequently but no one knows the reason for doing it one way or the other.

One theory I have heard is that smaller more frequent changes can agitate the corals but helps to keep water values in the right region which is why I have asked about water changes and values

 

[andywg]

Remember that doing a 25% water change biweekly will be more efficient than doing a 10% weekly water change, at least that's what I have been led to believe. Think: "Is there more water in the wine or more wine in the water"?

It's simple maths:

A 25% water change will remove 25% of the tank's volume.

a 10% water change will remove 10% of the tank's volume. The second water change will remove 10% of the water's volume, but the tank is now only 90% old water and 10% new water, so the second change is actually only removing 9% of the water that was in the tank originally.

Because of the above a pair of 10% water changes will not be as beneficial for replacing water as 1 20% (the former providing 19% removal).

This becomes more pronounced when looking at say 1 40% change against 4 10% changes. Each subsequent 10% change is removing less and less of the original amount and more and more "new" water. I think that Bignose posted a good link on it a while ago.

 

[Lynden]

That "water in the wine" thing was actually a problem found in my math book, according to that book it is a common riddle. It caused me to be more cautious with water changes. Heh, I suppose I shouldn't be bitching about how "I'm never gonna use this math"...

 

[SkiFletch]

Agree with Andy. And instead of typing up the whole big thing, just go ahead and read Water Changes in Reef Aquaria

 

[SkiFletch]

To add, I try and keep my tank within the following ranges:

Temp: 76-77 in the winter, 82-83 in the summer
sg: 1.024-1.026
pH: 8.0-8.4
Ammonia/Nitrite: 0
Nitrate: 0-20ppm
Phosphate: 0-0.03ppm
Calcium: 400-450ppm
Alkalinity: 9-12dKH
Magnesium: 1250-1350ppm

If values of calc, alk, or mg are too low, I will dose to increase those. If any other level is too high I will appropriately waterchange to get it down. I'm not afraid to do BIG waterchanges if necessary (50% and higher).

I waterchange 25% on a bi-weekly basis

 

[jeasko]

Guess i need to rethink my water change regime as i have only been doing 10% weekly, could be why my nitrates at 20ppm, off to the LFS tomorrow then!

 

[jeasko]

Ok so checked my nitrates again and they were between 30-40ppm which I think is high so done a water change again and no different which worries me a bit, i did however clean the filter out and powerheads but am wondering what else I can do to lower the nitrates?

any suggestions

 

[andywg]

Ok so checked my nitrates again and they were between 30-40ppm which I think is high so done a water change again and no different which worries me a bit, i did however clean the filter out and powerheads but am wondering what else I can do to lower the nitrates?

any suggestions

Get a second opinion on the tests.

I had no luck with API nitrate test kits and was told that fresh RO water with salt had 160ppm nitrates in it.

Try and get your lfs to test it with a different brand of test.

 

[chrissaysyes]

Btw, there isnt anything terrible with 10% weekly changes.