evaporation

Was hoping to get everones thoughts on something. My 120 (open top) evaporates about a gallon of water a day. (sometime a little more) That is about 31 gallons of water a month. (yes I did that math in my head) ;D My question is how does this compare to doing a water change? I'm assuming that a water change is different because when you pull out water you pull out other things with it, to where evaporation is nothing but water leaving the tank.

Please don't interperate this that I think I do not have to do water change because I do them. I'm just curious

 

I think what you're asking is if the top off water to balance out the evaporation should be fresh water? Then the answer is yes, b/c the salt etc doesn't evaporate with the water.

 

sorry, no I got that. I have an auto top off system with fresh water but the evaportation rate of the tank is about 1 gallon a day. Which means I am (the auot top off) is adding 1 gallon a day of fresh water or 31 gallons a month.

This being said. We all do water changes some more thatn others but let's just say that I do a 20 gallon water change this month. In addition to that my tank will evaporate 31 gallons. So that means that 51 gallons of water in my tank has been replaced one way or another, either through evaporation or the water change.

I guess my question is... Could this create a situtation where I am taking out too much water? My guess is no... The water change is pulling out salt, calcium, nitrates, nitrites (if there are any) to where the evaporation is taking nothing but water. Just wanted to get everyone elses thoughts.

 

As of the last month, I'm experimenting with not doing any water changes.
I'm just adding top off water, testing my parameters, and dosing what's needed.
Nothing seems affected so far, so I'm assuming as long as nitrates don't start building up everything should remain just fine. I don't have a coil denitrator set up yet.

 

I think I get what you're asking.

I see it this way. The point of a Water Change is not to add fresh or clean saltwater. The *point* is to remove nasty or depleted water and to replace it with (let's call it) enriched water full of elements, etc.

Top off water isn't enriched (you know, with a salt mix that will add Ca and buffers, etc).

My nitrates and phosphates have stayed low (0 and .5). My WC isn't to remove those, but as my preferred way of dosing.

If that makes sense. In any event, I don't think your top off plays into your WC at all.

 

Water changes and top-off are like apples and turkey. They can not be used interchangeably or one in the same as far as context is concerned. The two don not compare as top offs only replenish FRESHWATER lost through evaporation and nothing else. Water changes replenish trace elements, salts, minerals and also rid tank water of excess nutrients, dissolved organics and inorganics, add oxygen rich water at the same time removing dissolved carbon dioxide.
That is it in a nutshell!

 

I have thought of that myself, but always have had better results with water changes...

 

Like Bogie, I have been experimenting with the no water change idea as well. I just do twice weekly testing and keep my params in order, dose with trace elements and go with the flow. I do run a denitrator and it is keeping up nicely.

Unfortunately, I am in the midst of a cyano bloom. Now I must do a water change. I am bummed.

 

Do you think this cyano bloom has anything to do with the no WC experiment?

 

No, the first two things that popped into my head were (1) the stage my tank is in [ITO age] and (2) I have been overfeeding (nursing my skinny tang back to health). There are plenty of aquarists out there who do not do water changes and have no problems with it. So that is what I was thinking.

Good point though.