Rookie Water Change Question

[gleconte]

I feel really bad asking this question, but after searching the internet, the time has come. What formula should I use when determining how much salt to mix into my water changes? I would think that you match it to the main tank, but experiences shows that if I do that I get spikes in salinity. Thank you for your patience.

[evsalty]

Yes you should match it to the salinity of the tank the new water is going into. You should only be replacing what you are removing to prevent changes to your tanks salinity. If you are doing that then perhaps you are not letting your new water mix up long enough for all the salt to disolve.

Can you list how you are doing water changes typically?

[chuckreef]

What do you mean by: "I get spikes in salinty?"

[reef_doug]

Do you have a refractometer?
Most brands roughly suggest 1/2c per gallon, then fine tune it by measuring it. There is no exact amount of salt to gallon since different brands will have varying amounts of chlorides and such.

As esalty mentioned above, your new water should match the display... but if your display is higher then you want then you can use lower salinity water to help reach your total goal.

Many people target 1.025-1.026 for reef or 1.023 - 1.025 for fish only tanks.

[gleconte]

Yes you should match it to the salinity of the tank the new water is going into. You should only be replacing what you are removing to prevent changes to your tanks salinity. If you are doing that then perhaps you are not letting your new water mix up long enough for all the salt to disolve.

Can you list how you are doing water changes typically?

It looks like the problem has been that I wasn't being specific enough with how much water is being transferred. This makes sense. Thank you!

[EllieSuz]

Something worth mentioning is that water temperature affects salinity. Your new saltwater should be the same temperature as your Display and salt added (or water added) to get the right salinity. Keep a small powerhead and a heater in the container in which you make new saltwater and make it in advance of your water change to be sure it's adequately stirred and oxygenated.

[bertoni]

For smaller water changes (up to at least 15%), the temperature of the water isn't very important. Most of our measuring devices compensate for temperature, so heating the water isn't necessary. Letting the water mix until the pH is acceptable is a reasonable idea. Some (but not all) product mix up to a very high pH.

For large water changes, which I would avoid except in emergencies, getting the water temperature closer to the tank water might be appropriate, depending on the situation.

[evsalty]

It looks like the problem has been that I wasn't being specific enough with how much water is being transferred. This makes sense. Thank you!

For me, I always make sure that my water level is topped off before I take any water out. Then I add my new water until I reach that same level.