CAN A WATER CHANGE CAUSE A DKH SWING?

PeterB113

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Hey guys I'm wondering if I could possibly be causing dkh swings in my tank by doing 5g water changes every week in my 20g long reef tank. Everything looks fine but when I do my water changes my euphyllia shrinks up for about a day and then back to normal again. Is this normal?? I just want to get a routine down and not change it. I have a 20g long I use red sea coral pro and mix it myself with RODI water. Every week I mix it up to 1.025 Salinity and wait for PH to stableizie the do a 25% water change.(some people have said they think that is excessive). What do you guys think I have mainly LPS and soft corals and maybe 2 or 3 SPS. I feed the fish once a day,(I have 3 different types of frozen food that I switch off feeding) and then once a week feed my corals with reef roids, marine snow and fuel all mixed together.

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PeterB113

PeterB113

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Have you tested the Alk of the tank water and the fresh saltwater you're mixing up? If they are vastly different it could irritate some corals.
Red sea mixes to around 10.2 dkh and my tank the day of a water change usually reads around 9.2 to 9.5. Is that a dangerous swing?
 
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PeterB113

PeterB113

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What is dKH after water change? I doubt you raised it .7 dKH.

Are you using large, weekly water changes to maintain Alk & Ca? (No dosing)
Dkh of tank day before water change is around 9.2 to 9.5 then my fresh salt mixes to 10.2 after a water change its around 9.8 to 10 dkh
 
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Eagle_Steve

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Then that is more than 25% water change.
This right here.

OP are taking into account the sand, rocks, etc? All tanks hold less water than advertised, especially with these in them. For example, my 180 is only about 110 gallons even with a 40 gallon sump. I have lots of sand and rocks.
 
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PeterB113

PeterB113

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This right here.

OP are taking into account the sand, rocks, etc? All tanks hold less water than advertised, especially with these in them. For example, my 180 is only about 110 gallons even with a 40 gallon sump. I have lots of sand and rocks.
So are you guys saying to take out less water every week?
 

Randy Holmes-Farley

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So are you guys saying to take out less water every week?

Obviously, if you have measured the alk rise and are concerned about it, then change water in lower portions (a real 25 % is fine, as I showed) or use a different salt mix. :)
 

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