Do you adjust RODI top off ALK

[erics210]

Hello All.
Been wondering why I have such drops in all over time and makes sense that the evaporated water leaving my tank is being replaced with lower alk rodi water.
Does anyone adjust all in their rodi water coming in or is it always adjusted in the main display?

Just set up my soda ask 2 part to dose every 3 hours for 5 minutes giving me the 40 MLS or so I need to maintain 9dKH.

Thoughts?

 

[MadReefer]

I used to drip into the RODI but ran into problems of Alk being real high. I assumed not evaporation so the Alk built up and when RODI kicked in spiked up alk.
No drip into the skimmer compartment and its been pretty consistent.

 

[erics210]

I set up to drip into sump before return pump. Only 5 minutes but 8 times a day so it will hopefully keep it more balanced.
Was just wondering if anyone raised the dkh on their top off water.
I am not gonna do both...
Was just wondering if I raised my alk in the rodi. Would I not have to dose.
It seems that the new RODI water with lower alk is the reason I need to dose.

 

[Mark_C]

I'm not 2 parting, just kalkwasser. I'm running a stirrer between the ato and sump.
It works well and is incredibly easy to use. I test 1x per week and if the alk drops below 7.5 I drop 1/2 cup of kw into the stirrer.
Evaporation rate doesn't seem to be a major factor as the most fluctuation i see is only a few decimals up or down.
Currently I'm slowly increasing to get between 8-9, which simply involves upping the dose to 2/3 cup of kw.
I only picked up the stirrer about 2 months back and now that I have it I wont run another tank without one.

 

[amado]

When your salt water evaporates you alk/calcium stay in the tank only water H2O
Evaporates so you replace water with water.
what’s consuming alk in your tank is your corals or coralline algae. So you have to replace what your corals are using with salt water changes or dosing 2 part or kalk wasser

 

[erics210]

But wouldn't adding a couple gallons of rodi water which is all of 3-4-5 lower the alk of the tank?

 

[amado]

But wouldn't adding a couple gallons of rodi water which is all of 3-4-5 lower the alk of the tank?

No alk doesn’t evaporate it stays in the water. The reason you have to add alk is because your corals use it. The same thing with salt. Salt stays in the water it doesn’t evaporate so we just add more RODi water.
to keep salinity the same. RODi should have zero alk