water top up vs water change

[xpace]

Guys,

just a quick one for the future reference as my tank is still in cycle.

If my water evaporates about 5g a week (59g tank - marine), do I need to do water changes or simply just toping up will do ? that's all I do now considering there is no fish yet. using RODI water

thanks

[swck1]

pure water top off is more about keeping the sg the same. water change is about removing dirty ( fish poop leftover food waste ) and replacing with fresh salt water.

[jamesbaur13]

Top off water isn't the same as water change.

Here's how it works.

You have freshwater, you add salt to it to make saltwater. As the water evaporates the salt is left behind. This increases the ratio of salt per gallon. To counteract this increase and to maintain your desired level of salinity you dillute the salt via topping off with freshwater. If you were to top off with saltwater it would raise your salinity... the water evaporates, the salt (and other minerals) are left behind.

When you are doing water changes you are exchanging your old saltwater with new saltwater. What this does is removes nitrate from your old water as well as it replaces some minerals that were depleted. Salt mix contains more than just salt... it contains all the elements your tank inhabitants will need.

[Danzig]

Originally Posted by jamesbaur13

Top off water isn't the same as water change.

Here's how it works.

You have freshwater, you add salt to it to make saltwater. As the water evaporates the salt is left behind. This increases the ratio of salt per gallon. To counteract this increase and to maintain your desired level of salinity you dillute the salt via topping off with freshwater. If you were to top off with saltwater it would raise your salinity... the water evaporates, the salt (and other minerals) are left behind.

When you are doing water changes you are exchanging your old saltwater with new saltwater. What this does is removes nitrate from your old water as well as it replaces some minerals that were depleted. Salt mix contains more than just salt... it contains all the elements your tank inhabitants will need.

Great post! this is probably the best answer you will find to your question.

[daplatapus]

I read several guys posts on here and other forums that haven't done water changes in over a year, just did their top offs and their tanks looked great. How accurate their circumstances are... I don't know. I tried only topping off for about 2 months. All my fish seemed fine, all my water parameters were perfect. But do you think I could get any corals to grow? Not on your life. I've been doing 25-30 gallon water changes with fresh salt water every week for the last 3 weeks and everything has exploded with life. My sps corals don't even look like the same corals.
Water changes will replenish all the little trace elements we don't test or dose nut are still crucial for the survival of your tanks inhabitants.

[xpace]

well explained

thank you


---
I am here: http://maps.google.com/maps?ll=-33.757791,151.296623

[dimitrge]

I agree with the above posts. Reg water changes once a week is a good habit. I have an ato with a 5g tank for top off. You will see a difference in the way the corals react when a water change is done vs just toppin off.

[zeeter]

I guess the guys who don't do water changes are doing some major dosing in their tanks to replenish the trace elements.

[Barrier Grief]

Tagging along - I'm starting a 90 gal reef tank after many years of having a FO tank years ago. When doing WC in reef tank, in addition to matching salinity/temp, is it also necessary to match pH, Ca, Mg, Alk in new water? I'm planning to dose Kalk in ATO, but that seems irrelevant in handling Ca, Mg, Alk depletion due to WC.

[Randy Holmes-Farley]

It isn't necessary to match anything aside from temp and salinity, and even then it isn 't necessary if you do very small, very frequent changes.

[pscott99]

http://www.reefcentral.com/forums/sh....php?t=2100653


Since I recently read a technical article on the fact that skimmers only remove 30 % of the bad stuff I am more diligent on the water changes.

I am doing 5% a week, others do 10 %.

Randy is a great read also. Randy Holmes-Farley Reefkeeping

[pscott99]

That's too funny Randy. I typed too slow.

[Randy Holmes-Farley]

Happy Reefing.

[mikeweber3]

In my opinion (which is based on years of experience) If you have aq well balanced system, ie plant life in a refuguim, plenum for nitrate removal, and if you don't feed a lot you don't need a skimmer or water changes.
all I do is dose a little magnesium, iodine, strontium and molybedium once per week. It does work for me.

Thanks

Mike

[Barrier Grief]

Thanks all - and yes, I'm planning smaller/more frequent WC as opposed to bigger ones less frequently

Randy - So, I understand the thinking instead of just the conclusion, is the Ca, Mg, Alk loss due to WC just proportionately insignificant to the balance left in the tank such that the loss is assumed negligible? Seems if this is done indefinitely without eventually adding some of each in addition to ATO kalk, that levels all would deplete to residual levels over time. I must have to add back eventually - no? Is your answer assuming I will periodically add to boost levels to desired mid-ranges via two part solution as part of routine maintenance?

[Randy Holmes-Farley]

I meant it wasn't necessary from the standpoint of shocking animals. If the salt mix has a lot more or less of an important ion than the tank does, you 'd probably want to consider that in your overall dosing scheme. If something is being depleted by the tank, then water changes can help bring it up. Likewise, if something is accumulating, water changes can help bring it down again.