Auto Water Change - Salt Change Idea (higher alk / cal to reduce daily two part input)

[mattdg]

I have recently successfully implemented an auto water change system into my 120 gallon mixed reef, and I absolutely love it.

I'd now like to pick your brains regarding the salt I am using and the one I may start using.

Currently I mix up around 55 gallons of Red Sea salt, every month or so. No complaints, it's a high quality salt mix that mixes clean and leaves no residue. I change around 1 gallon / day in my 120 gallon SPS heavy reef, using the AWC.

The parameters of the salt, nearly perfectly match the parameters of the tank, as originally intended. The coral looks amazing and has given me a clear thumbs up (polyps up?) in the form of color, polyp extension and rapid healing, post fragging.

Tank parameters are around 8 Alk / 400 Cal / 1275 Mag I plan to maintain these parameters.

I originally went this route, due to the fact that I used to perform 15 gallon water changes every other week and I didn't want to cause an extreme parameter shift when moving that volume of water in and out of the tank.

However, now theoretically it doesn't really matter if the salt has higher base parameters, than my aquarium, so long as I adjust my Alk/Cal/Magnesium dose down a bit to compensate for the daily 1 gallon water change. I can't imagine 1 gallon / day WC causing any meaningful shift in Alk/Cal, more like an additional two part dose. At least, that's my theory. The idea is that I may even save a bit of $$, given the Red Sea Coral Pro salt mix is only slightly more expensive to purchase and will make up part of my reefs daily alk / cal uptake, while changing out old and new SW. What are your thoughts on that?

Second benefit may be Red Sea Coral Pro salt mix includes higher trace amounts. Currently, I add red sea trace colors into my fresh saltwater reservoir, based on monthly calcium uptake, which is an added expense. If the mix already includes these elements (does anyone know if it does?), I may simply test at the end of the month and use the red sea colors to adjust whatever elements are low.

For those of you who run an Auto Water Change setup, I'd like to hear your thoughts on what salt you use and why, what you think about using a salt with higher parameters/trace and any additional suggestions or benefits you might suggest, when it comes to using an AWC setup.

Thanks

 

[Randy Holmes-Farley]

Unless your demand is very low, or you change massive amounts, this method will fail.

Suppose the salt is 5 dKH higher than your tank, and you change 1% daily (that what I used), you will only effectively be adding 5 dKH x 0.01 = 0.05 dKH per day. That's about 10-50 times too little for most tanks.

You cannot boost new salt water to the levels of alk needed to make this work.

 

[mattdg]

Unless your demand is very low, or you change massive amounts, this method will fail.

Suppose the salt is 5 dKH higher than your tank, and you change 1% daily (that what I used), you will only effectively be adding 5 dKH x 0.01 = 0.05 dKH per day. That's about 10-50 times too little for most tanks.

You cannot boost new salt water to the levels of alk needed to make this work.

Absolutely agree! My aquarium consumes well over 100 ml of BRS two part per day, so it would take around a 75% daily water change, to maintain the aquarium at 8dKH.

I can see that I wasn't clear in my post above that I will continue to dose two part, but will reduce the dose by several ml / day, to compensate for the higher alklinity being added with the daily 1 gallon water change. It's seems straightforward, but wondering if I'm missing anything here.

I'd like to maintain my system at 8, even though the new water is close to 12dKH.

On a side note, I am close, but perhaps I should increase my daily water change to 1% daily? Has that been an ideal ratio for you?

 

[Randy Holmes-Farley]

I didn't really mess with different daily change ratios to determine what might be best. I do have an article that details what can be accomplished with different types and sizes of water changes that might help:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

100 mL of the DIY recipe#1 (that BRS uses with soda ash) added to 120 gallons boosts alk by 1.2 dKh per day. The added 0.04 dKH from the water change is likely just lost in the noise, but will reduce the need for two part a tiny bit.

This discussion points out the beauty of an AWC where you do lots of small changes each day: Nothing needs to match the tank. Not salinity or temp or alk or anything. You just need to be aware of what change those differences might make.