Water change and 3 dead tridacnids???

[Chris Harbaugh]

I need help. I use Red Sea salts and i did a water change after 3 weeks. I have a 125g with a 55g refugium and a 30g with a 20g refugium. I changed 10g in the 30g tank with 3 clams, 2 squamosa and 1 maxima. I changed 40 gallons in my 125g which had 2 maximas, 1 derasa, and 1 hippopus. I lost one of my squamosa in th 30g and 1 maxima and my derasa in my 125g. I have never done it before, but i mixed my saltwater 2 weeks ago and there was a powdery residue in the bottom of my drum. I used this.. im extremely upset as all of my clams were doing so great. Am i letting my saltwater mixture age too long?? I have been told its best to let it age.. is this true.. im doing another water change now.. 2 days later..

 

[wkscott]

Sorry for your loss.

Was the new water clear or cloudy when you poured it into the tank?

Did you heat AND aerate it before putting it in?

 

[Chris Harbaugh]

The water was clear until the last 10 gallons. All of that went into my 125g. Heated. No. The temp in my tank was at 79 degrees and the new water in was at 72 degrees. I really didnt think it was going to be a problem. Aerate??? Im feeling real stupid because i dont know what that is or the process. Now im feeling stupid.. can you elaborate on this??

 

[Chris Harbaugh]

Both of my tanks run a steady 79 degrees. My 30g will drop to 78 every now and then.

 

[wkscott]

Your replacement water should closely match the temp in the tank or you can shock or worse, kill some of your most sensitive creatures, clams included. It is best to have the new water within 2°F of the tank water.

Water that has just been sitting for a couple of weeks could have a low oxygen level and/or or high CO2 levels.
This could cause your alkalinity to greatly decrease. This alkalinity swing could also shock your tank.
By aerating the water for at least an hour (while you're heating it) lessens both issues. You aerate it by using an airstone(s) and a strong air pump, or by placing a water pump towards the surface of the water to ensure high surface agitation.
My prepared saltwater sits for 4 weeks sometimes in covered containers and I heat and aerate for 2 hours just prior to use. This stirs up the white powder you noticed and helps to disolve it before pouring into the tank.

 

[Chris Harbaugh]

Thank you.. really. I didnt think the temp was that much of a concern. Im wrong.. i want my water colder because the new water sinks and the old water rises and drains into my refugium and thats how i change my water. I use my pump, at low setting to pump out then i add new water. All is measured via buckets. A slow process but until now ive had no problems. I have had my deresa for more than 6 months.. just never had a problem before. I will change up. I tbink i will also not let my mix sit that long. I have always mixed and changed my water within hours. I only checked my salinity and temp.. i will make sure my temp is closer to 79 from now on.. i have just never checked the alk. I will start doing that though after putting a powerhead in the water.. i dont know how to check for CO2 though..

 

[wkscott]

Thank you.. really. I didnt think the temp was that much of a concern. Im wrong.. i want my water colder because the new water sinks and the old water rises and drains into my refugium and thats how i change my water. I use my pump, at low setting to pump out then i add new water. All is measured via buckets. A slow process but until now ive had no problems. I have had my deresa for more than 6 months.. just never had a problem before. I will change up. I tbink i will also not let my mix sit that long. I have always mixed and changed my water within hours. I only checked my salinity and temp.. i will make sure my temp is closer to 79 from now on.. i have just never checked the alk. I will start doing that though after putting a powerhead in the water.. i dont know how to check for CO2 though..

Sounds good. You don't need to check for CO2, mixing the water fresh will drive it off and aerate at the same time.
The colder water does sink as you say but the 7° immediate drop in temperature, especially on the creatures at the bottom of the tank can be very stressful.