How to Make a Safe Water Change for Marine Fish

leebca · 10-12-2007, 04:02 PM

Few experienced aquarists give much thought to making water changes. It has become second nature. The advanced and experienced aquarists take it for granted. For the beginner, the nuances and attention to water changes can mean a happy fish or a dead fish,

and anything in between. So here is one way to perform a water change to make a happy fish:

1. Make sure you're using proper source water free of contaminants (including but not limited to: dissolved organics, ammonia, nitrites, pesticides, phosphates, nitrates, silica compounds, smell, and poisons). If there is any doubt as to the quality of the source water, test it. Artificial salt manufacturers who recommend using tap water as the source water are wrong. The variations of tap water quality around the world make it range from marginally good to horrible. Even when found marginally good, will it be consistently good? Get more information about the downside to using tap water here: Chemistry and the Aquarium

2. Mix the source water, preferably using a submersible (inside aquarium) pump (not an aerator). The water should move up and down in the mixing container, not around in a circle. In this way, the water doesn't take on excess air/carbon dioxide, and mixes quickly and thoroughly. Choose a mixing place away from household chemicals (for instance, don't mix salt water in the laundry room, paint shed, garage where cars are parked, etc.).

3. Add the artificial salt to the water, in the quantity required to get close to the marine system's specific gravity.

4. Mix the salt according to the salt manufacturer's directions (as to how long to mix). (NOTE: The salt manufacturer should know how best to mix their salt into water, however studies have shown that the most stabilized water is achieved after about a week of mixing. This extended time is connected to gas exchange and the chemical reactions going on in the water between the various salts and the gases in the surrounding air.) In no case would I recommend mixing for less than 48 hours. It has been discovered that bad salt mixes will usually 'show themselves out' within the first 48 hours of mixing. If the mixed salt is cloudy or partially undissolved in 48 hours, there is something wrong. No good salt mix should leave a noticeable residue. (NOTE: Some unusual/less common artificial salt manufacturers may depend upon mixing to chemically react their chosen ingredients. Such manufacturers can recommend up to and including 2 weeks of mixing!).

5. After mixed, check the specific gravity of the prepared water. [NOTE: If the salt mix is not properly balanced to provide the proper calcium, alkalinity, and magnesium, now is an opportunity to bring those chemistries into the desired range with the chemistries in the marine system.] The specific gravity of the new water should match as closely as you can with the specific gravity of the water it will replace. Usually, matching to within 0.001 sp. gr. unit is acceptable. Adjust the new water by adding a little more salt, or adding some source water. If a lot of salt had to be added (more than 2% of what you've already added) then go back to 4.

6. When the specific gravity of the new water matches the marine system water specific gravity, measure the pH and temperature of the marine system and the new water. Adjust pH and temperature of the new water to that of the marine system water. (NOTE: This is one of the places of the biggest common error -- the pH adjustment. The pH of the new and old water must be extremely close -- to within 0.05 pH units, if possible). The temperature of the new water should be no lower, and can be up to 1.5F higher than the marine system water. As the volume of the water change goes up, the more important controlling these two qualities becomes. 10% or less water changes can get away with lesser control.

7. Remove the water from the marine system. You can take advantage of siphoning in order to clean out detritus/debris around in the display tank, QT, sump, and/or refugium.

8. Add the new water to the marine system.

After the above, it is important to replace evaporated water with distilled water (if you have a small aquarium), or RO/DI or deionized water for larger systems. Maintain a constant specific gravity of the marine system, a constant pH in the proper zone, and a near constant temperature.

Some interesting information and things to know:
a. A sudden drop in temperature as little as 2F in an hour can cause a marine fish mucous coating to sluff off or improperly function. This causes the fish to become sensitive to infection and diseases it could otherwise fend off. This is the reason why fish who go through a drop in temperature suddenly become ill or infected. A small drop in temperature is significantly far worse than a small rise in temperature.

b. pH is measured not in 'straight numbers' but in a logarithmic function of the hydrogen ion concentration. A small change in pH number is a large change in concentration of the hydrogen ion. What seems like a small numerical change is actually a large chemical change. Don't be fooled. A pH change of 0.10 pH units is significant to a marine fish that has never known the pH of its home waters to change by more than 0.01 units over the period of a year!

c. Salinity sets up the way the fish's internal chemistries function. The fish's internal physiology is based upon the fish's environment and that environment is the water, how much salt is in that water, and how clean that water ultimately is with regards to its home water quality. A fish can handle a rather rapid lowering of salinity (specific gravity) but not an increase in salinity. If salinity drifts too low in the system, raise it slowly (no more than 0.002 sp. gr. units per day). The fish's internal chemistries need time to adjust to a change in salt concentration in the water.

d. Chemicals to make pH adjustments need to be compatible with the marine system. Small adjustments can be made with fresh and pure Baking Soda found in the grocery store. This is sodium bicarbonate. Too much of this and it throws off the alkalinity and the pH control is pretty much lost. Another useful pH adjusting chemical is sodium carbonate. Less is needed to raise the pH. You can make this at home by heating pure fresh Baking Soda, spread out on a pan, in a preheated oven at 350F for 40 minutes and letting it cool. This will change the pH up (raise the pH quicker, and less is needed and thus less likely to throw off the alkalinity). Other suitable chemicals are sodium hydroxide (liquid or pellets). No one can say how much of any of these chemicals to use. This is in part because no one knows the starting pH and the strength of the buffer of the salt water you made up. It is trial and error. Just add a very little bit then check its effect on the pH of your batch. pH should be checked by a meter, NOT by a test kit.

Making the fish think the water is cleaner but hasn't changed in pH, temperature or salinity is the key to a good water change!

Hope this helps.

Woodstock · 10-12-2007, 04:31 PM

Great info! Thanks Lee!

Dentoid · 10-12-2007, 04:59 PM

Thanks again Lee! You're a gem! Or did I already say that somewhere?

zimboy · 10-12-2007, 05:01 PM

one comment, i believe the temp should be adjusted first before the salinity, as different temps will result in different salinity readings. Please correct me if i'm wrong.

Adam

P.S. excellent advice

jaysthename · 10-12-2007, 06:10 PM

Quote:

Originally Posted by leebca

5. After mixed, check the specific gravity of the prepared water. [NOTE: If the salt mix is not properly balanced to provide the proper calcium, alkalinity, and magnesium, now is an opportunity to bring those chemistries into the desired range with the chemistries in the marine system.] The specific gravity of the new water should match as closely as you can with the specific gravity of the water it will replace. Usually, matching to within 0.001 sp. gr. unit is acceptable. Adjust the new water by adding a little more salt, or adding some source water. If a lot of salt had to be added (more than 2% of what you've already added) then go back to 4.

Is this a typo by any chance? Because I don't know how in the world I would get to within 0.001 specific gravity. My hydrometer doesn't even measure into the thousandths, and even if it did, I know it wouldn't be that accurate. Are you by chance using some fancy digital hydrometer to get readings that precise?

leebca · 10-12-2007, 06:34 PM

Adam,

Generally speaking it can go either way. The pump (after 48 hours) will usually have warmed the water. After a week of mixing it may be warmer than the marine system. Salinity does change with temperature, but I envision that there is a significant higher probability that the hobbyist will not hit the salinity right on, but need to tweak it some.

If the pump sends enough heat to the water and the hobbyist has to add more salt and mix longer, the temperature would need a second adjustment if it was first adjusted. The proposed method requires one temperature adjustment with likely little effect on the salinity. BUT if you are dealing with a great temperature difference between water and marine system (like mixing new water outdoors during the winter) your way would be the wisest choice.

leebca · 10-12-2007, 06:37 PM

Not a typo jay but it could be clearer.

You want to get within 0.001 specific gravity units of the specific gravity of the marine system.

An example would be a specific gravity reading of 1.025 on the marine system water. The goal would be to get the new water between 1.024 and 1.026 specific gravity units (or within 0.001 specific gravity units of what was measured on the marine system water).

A good hydrometer would measure reliably enough for keeping specific gravity in this range. If yours doesn't, it would be worth switching to a refractometer which is less than $40. or a better hydrometer. If you're using one with a 'swing arm' I'd smash it and tell your sig. other you need to buy a new one (then get either a good hydrometer or a refractometer).

Melanie · 10-12-2007, 08:39 PM

Lee, I really enjoy your posts. I wish I could express how much I appreciate your writing as eloquently as you give advice.

Witfull · 10-13-2007, 02:13 AM

im so glad i found Lee, and it was only because of a purgurist stealing Lee's work and posting it as his.

(witty has detective skills)

leebca · 10-13-2007, 04:55 AM

Thanks to all for your kind sentiments.

lcstorc · 10-13-2007, 12:45 PM

More great information.
Thanks

jaysthename · 10-17-2007, 08:40 PM

Thanks so much for the info, Lee. My lfs did in fact saddle me with a swing-arm hydrometer, and I was too much of a newbie to realize it wasn't ideal. I'll put a refractometer on the Christmas list

Quote:

Originally Posted by leebca

Not a typo jay but it could be clearer.

You want to get within 0.001 specific gravity units of the specific gravity of the marine system.

An example would be a specific gravity reading of 1.025 on the marine system water. The goal would be to get the new water between 1.024 and 1.026 specific gravity units (or within 0.001 specific gravity units of what was measured on the marine system water).

A good hydrometer would measure reliably enough for keeping specific gravity in this range. If yours doesn't, it would be worth switching to a refractometer which is less than $40. or a better hydrometer. If you're using one with a 'swing arm' I'd smash it and tell your sig. other you need to buy a new one (then get either a good hydrometer or a refractometer).

10-12-2007, 04:02 PM	#1 (permalink)
leebca Pistol Shrimp Join Date: Jul 2007 Location: So CA Posts: 272 View Gallery Karma Komment	How to Make a Safe Water Change for Marine Fish Few experienced aquarists give much thought to making water changes. It has become second nature. The advanced and experienced aquarists take it for granted. For the beginner, the nuances and attention to water changes can mean a happy fish or a dead fish, and anything in between. So here is one way to perform a water change to make a happy fish: 1. Make sure you're using proper source water free of contaminants (including but not limited to: dissolved organics, ammonia, nitrites, pesticides, phosphates, nitrates, silica compounds, smell, and poisons). If there is any doubt as to the quality of the source water, test it. Artificial salt manufacturers who recommend using tap water as the source water are wrong. The variations of tap water quality around the world make it range from marginally good to horrible. Even when found marginally good, will it be consistently good? Get more information about the downside to using tap water here: Chemistry and the Aquarium 2. Mix the source water, preferably using a submersible (inside aquarium) pump (not an aerator). The water should move up and down in the mixing container, not around in a circle. In this way, the water doesn't take on excess air/carbon dioxide, and mixes quickly and thoroughly. Choose a mixing place away from household chemicals (for instance, don't mix salt water in the laundry room, paint shed, garage where cars are parked, etc.). 3. Add the artificial salt to the water, in the quantity required to get close to the marine system's specific gravity. 4. Mix the salt according to the salt manufacturer's directions (as to how long to mix). (NOTE: The salt manufacturer should know how best to mix their salt into water, however studies have shown that the most stabilized water is achieved after about a week of mixing. This extended time is connected to gas exchange and the chemical reactions going on in the water between the various salts and the gases in the surrounding air.) In no case would I recommend mixing for less than 48 hours. It has been discovered that bad salt mixes will usually 'show themselves out' within the first 48 hours of mixing. If the mixed salt is cloudy or partially undissolved in 48 hours, there is something wrong. No good salt mix should leave a noticeable residue. (NOTE: Some unusual/less common artificial salt manufacturers may depend upon mixing to chemically react their chosen ingredients. Such manufacturers can recommend up to and including 2 weeks of mixing!). 5. After mixed, check the specific gravity of the prepared water. [NOTE: If the salt mix is not properly balanced to provide the proper calcium, alkalinity, and magnesium, now is an opportunity to bring those chemistries into the desired range with the chemistries in the marine system.] The specific gravity of the new water should match as closely as you can with the specific gravity of the water it will replace. Usually, matching to within 0.001 sp. gr. unit is acceptable. Adjust the new water by adding a little more salt, or adding some source water. If a lot of salt had to be added (more than 2% of what you've already added) then go back to 4. 6. When the specific gravity of the new water matches the marine system water specific gravity, measure the pH and temperature of the marine system and the new water. Adjust pH and temperature of the new water to that of the marine system water. (NOTE: This is one of the places of the biggest common error -- the pH adjustment. The pH of the new and old water must be extremely close -- to within 0.05 pH units, if possible). The temperature of the new water should be no lower, and can be up to 1.5F higher than the marine system water. As the volume of the water change goes up, the more important controlling these two qualities becomes. 10% or less water changes can get away with lesser control. 7. Remove the water from the marine system. You can take advantage of siphoning in order to clean out detritus/debris around in the display tank, QT, sump, and/or refugium. 8. Add the new water to the marine system. After the above, it is important to replace evaporated water with distilled water (if you have a small aquarium), or RO/DI or deionized water for larger systems. Maintain a constant specific gravity of the marine system, a constant pH in the proper zone, and a near constant temperature. Some interesting information and things to know: a. A sudden drop in temperature as little as 2F in an hour can cause a marine fish mucous coating to sluff off or improperly function. This causes the fish to become sensitive to infection and diseases it could otherwise fend off. This is the reason why fish who go through a drop in temperature suddenly become ill or infected. A small drop in temperature is significantly far worse than a small rise in temperature. b. pH is measured not in 'straight numbers' but in a logarithmic function of the hydrogen ion concentration. A small change in pH number is a large change in concentration of the hydrogen ion. What seems like a small numerical change is actually a large chemical change. Don't be fooled. A pH change of 0.10 pH units is significant to a marine fish that has never known the pH of its home waters to change by more than 0.01 units over the period of a year! c. Salinity sets up the way the fish's internal chemistries function. The fish's internal physiology is based upon the fish's environment and that environment is the water, how much salt is in that water, and how clean that water ultimately is with regards to its home water quality. A fish can handle a rather rapid lowering of salinity (specific gravity) but not an increase in salinity. If salinity drifts too low in the system, raise it slowly (no more than 0.002 sp. gr. units per day). The fish's internal chemistries need time to adjust to a change in salt concentration in the water. d. Chemicals to make pH adjustments need to be compatible with the marine system. Small adjustments can be made with fresh and pure Baking Soda found in the grocery store. This is sodium bicarbonate. Too much of this and it throws off the alkalinity and the pH control is pretty much lost. Another useful pH adjusting chemical is sodium carbonate. Less is needed to raise the pH. You can make this at home by heating pure fresh Baking Soda, spread out on a pan, in a preheated oven at 350F for 40 minutes and letting it cool. This will change the pH up (raise the pH quicker, and less is needed and thus less likely to throw off the alkalinity). Other suitable chemicals are sodium hydroxide (liquid or pellets). No one can say how much of any of these chemicals to use. This is in part because no one knows the starting pH and the strength of the buffer of the salt water you made up. It is trial and error. Just add a very little bit then check its effect on the pH of your batch. pH should be checked by a meter, NOT by a test kit. Making the fish think the water is cleaner but hasn't changed in pH, temperature or salinity is the key to a good water change! Hope this helps. __________________ LEE Last edited by leebca : 10-14-2007 at 08:33 AM. Reason: Added info on chemicals for pH adjustments

10-12-2007, 04:31 PM	#2 (permalink)
Woodstock The Wand Geek was here. ;) Join Date: Nov 2003 Location: North Carolina Posts: 22,553 View Gallery Karma Komment Add yours!	Re: How to Make a Safe Water Change for Marine Fish Great info! Thanks Lee! __________________ ~Doni Marie~ *GOT ICH???* ~120 Reef Chronicle ~ *~Breeding Picasso Clownfish~* "Energy and persistence conquer all things." Benjamin Franklin __________________________________________________ ______________________________________________ 120 mixed reef, dual Reeflux 10k 250 MHs, dual Geiseman Actinic T5s,Neptune AC III, ASM g3, 2x Korallia #3, Mag 9.5 return

10-12-2007, 04:59 PM	#3 (permalink)
Dentoid Over Achiever Join Date: Dec 2006 Location: Virginia Posts: 10,239 View Gallery Karma Komment	Re: How to Make a Safe Water Change for Marine Fish Thanks again Lee! You're a gem! Or did I already say that somewhere? __________________ Scott Dentoid's Reeforama

10-12-2007, 05:01 PM	#4 (permalink)
zimboy Tuxedo Urchin Join Date: Feb 2007 Location: Canada Posts: 296 View Gallery Karma Komment Add yours!	Re: How to Make a Safe Water Change for Marine Fish one comment, i believe the temp should be adjusted first before the salinity, as different temps will result in different salinity readings. Please correct me if i'm wrong. Adam P.S. excellent advice

10-12-2007, 06:34 PM	#6 (permalink)
leebca Pistol Shrimp Join Date: Jul 2007 Location: So CA Posts: 272 View Gallery Karma Komment	Re: How to Make a Safe Water Change for Marine Fish Adam, Generally speaking it can go either way. The pump (after 48 hours) will usually have warmed the water. After a week of mixing it may be warmer than the marine system. Salinity does change with temperature, but I envision that there is a significant higher probability that the hobbyist will not hit the salinity right on, but need to tweak it some. If the pump sends enough heat to the water and the hobbyist has to add more salt and mix longer, the temperature would need a second adjustment if it was first adjusted. The proposed method requires one temperature adjustment with likely little effect on the salinity. BUT if you are dealing with a great temperature difference between water and marine system (like mixing new water outdoors during the winter) your way would be the wisest choice. __________________ LEE

10-12-2007, 06:37 PM	#7 (permalink)
leebca Pistol Shrimp Join Date: Jul 2007 Location: So CA Posts: 272 View Gallery Karma Komment	Re: How to Make a Safe Water Change for Marine Fish Not a typo jay but it could be clearer. You want to get within 0.001 specific gravity units of the specific gravity of the marine system. An example would be a specific gravity reading of 1.025 on the marine system water. The goal would be to get the new water between 1.024 and 1.026 specific gravity units (or within 0.001 specific gravity units of what was measured on the marine system water). A good hydrometer would measure reliably enough for keeping specific gravity in this range. If yours doesn't, it would be worth switching to a refractometer which is less than $40. or a better hydrometer. If you're using one with a 'swing arm' I'd smash it and tell your sig. other you need to buy a new one (then get either a good hydrometer or a refractometer). __________________ LEE

10-12-2007, 08:39 PM	#8 (permalink)
Melanie Golden Moray Join Date: Jun 2007 Location: Naples, Florida Posts: 2,120 View Gallery Karma Komment Add yours!	Re: How to Make a Safe Water Change for Marine Fish Lee, I really enjoy your posts. I wish I could express how much I appreciate your writing as eloquently as you give advice. __________________ My Reef Journey Latest Recap My Videos My Flickr Photos Pres. of Dork Club I love ScubaDrew and North East Coral! Read why HERE...

10-13-2007, 04:55 AM	#10 (permalink)
leebca Pistol Shrimp Join Date: Jul 2007 Location: So CA Posts: 272 View Gallery Karma Komment	Re: How to Make a Safe Water Change for Marine Fish Thanks to all for your kind sentiments. __________________ LEE

10-13-2007, 12:45 PM	#11 (permalink)
lcstorc Sunshine Reefer Join Date: Mar 2006 Location: Cocoa Fl Posts: 17,965 View Gallery Karma Komment Add yours!	Re: How to Make a Safe Water Change for Marine Fish More great information. Thanks __________________ Peace LYNN You can't change the past but you can change how you view it. A reef tank is like a racecar. The faster you go the harder you crash. Lynn and Franks saltwater adventure Lynn's 20g clown tank Lynn's 90g of sunshine Every 60 seconds you spend upset is a minute of happiness you'll never get back.

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