Topping off freshwater aquarium with tap water?

Finthusiast

Candiru
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Is this safe to do without adding dechlor? Just wondering how dangerous this will be if I only add like 5 gallons to a 75 gallon tank just to top off evaporated water. Will I still need to treat my entire tank or is there not going to be significant amount of chloramines to cause harm?
 

Niki_up

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Is this safe to do without adding dechlor? Just wondering how dangerous this will be if I only add like 5 gallons to a 75 gallon tank just to top off evaporated water. Will I still need to treat my entire tank or is there not going to be significant amount of chloramines to cause harm?
If your only adding 5g of water why not just treat the 5g before adding it to your tank?
Why take the risk of adding untreated water?
 

TwoHedWlf

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Is this safe to do without adding dechlor? Just wondering how dangerous this will be if I only add like 5 gallons to a 75 gallon tank just to top off evaporated water. Will I still need to treat my entire tank or is there not going to be significant amount of chloramines to cause harm?
Not particularly dangerous, but why not just treat the 5 gallons before adding it?
 

Finthusiast

Candiru
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Thanks for the replys! Great solution, I did not think about that when I created this thread lol
 

Itsadeepbluesea

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What kind of water do you have? City or well? I have well and do all my water changes with "tap" water. If you have city water I would think it would be a good idea to treat top offs.
 

AaronKWolfe

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I agree with everybody else, if you have city water then dechlorinate it and potentially add in other things (like cichlid salt if you have cichlids depending on whether or not the water is already at the right hardness, pH, etc.). If you have well water then you don't need to dechlorinate, but you should still treat it if the parameters of your well water aren't the same with your tank.
 
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duanes

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I never just top off. Evaporation concentrates liquid waste products in the tank.
With a top off, you are basically concentrating the already concentrated soup of liquid fish waste even more.
I always figure, if you are going to take the time to top off, do a water change instead (even if its a small one of only a few gallons) at least in that way, you are diluting the soup, and adding new water.
 

DDK

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I agree with duanes but sometimes im busy and I cant wc so I top off. I dose the whole volume of water (in the tank) and then just throw the hose on the sink and top off with temp matched tap water. I use SAFE dechlorinator so its not breaking the bank, with liquid dechlorinators its questionable cause its pricey. 1/8th of a tablespoon treats 300 gallons so its cheap and saves me in a time bunch.

And chloramines is just chlorine mixed with ammonia which causes it not to evaporate off, but chloramines will likely dilute and be taken out by some filter muck. Disinfection is selective killing of microorganisms (pathogens in this case) and sterilization is complete killing of all microorganisms pathogens and beneficial bacteria. Chloramines effect pathogens better than regular microorganisms. When your topping off with such a small % and the % of chloramines in the water is 4ppm its virtually undetectable. ex if your tank is 100 gallons and you top off 10%(10 gallons), the chloramine content in the water will be diluted to .4 ppm which isnt going to hurt anything. Your beneficial bacteria is always dying and multiplying anyways and if the chloramines do make it to them before being consumed by tank muck its not going to harm the colony significantly, theyll be back to their regular numbers in a few hours if the food source permits.
 
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squint

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And chloramines is just chlorine mixed with ammonia which causes it not to evaporate off, but chloramines will likely dilute and be taken out by some filter muck. Disinfection is selective killing of microorganisms (pathogens in this case) and sterilization is complete killing of all microorganisms pathogens and beneficial bacteria. Chloramines effect pathogens better than regular microorganisms. When your topping off with such a small % and the % of chloramines in the water is 4ppm its virtually undetectable. ex if your tank is 100 gallons and you top off 10%(10 gallons), the chloramine content in the water will be diluted to .4 ppm which isnt going to hurt anything. Your beneficial bacteria is always dying and multiplying anyways and if the chloramines do make it to them before being consumed by tank muck its not going to harm the colony significantly, theyll be back to their regular numbers in a few hours if the food source permits.
Chlorine can react with organics. Chloramine probably won't, at least not very quickly. Even if it did, the reaction between chlorine and organics leads to the formation of organic chloramines which are just as toxic as chloramine while being more resistant to dechlorination. They also can't be detected using conventional tests.

0.4 mg/L chloramine is plenty dangerous.
 
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lp85253

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I agree with everybody else, if you have city water then dechlorinate it and potentially add in other things (like cichlid salt if you have cichlids depending on whether or not the water is already at the right hardness, pH, etc.). If you have well water then you don't need to dechlorinate, but you should still treat it if the parameters of your well water aren't the same with your tank.
*don't add salt * .. that adds to the salt content , evaporated water doesn't take the salt with it when it evaporates
 
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