Finding a balance with auto water changes

[certain_code]

Simple question for everyone. For anyone that is performing auto-water changes, how are you finding a balance with your additives?

I am currently running Versa dosers and changing 10 gallons a week on my tank. With running Brightwell Marine NeoMarine salt, I regularly measure 6.6dKH on the newly mixed salt (advertised as 7.5dKH) and I am trying to maintain roughly 7.5 dKH in my display. Given most "highly" rated salt mixes run roughly 7-8dKH, but in my experience have been closer to 6.7-7.2 dKH (measured via Hanna), how is everyone managing their Alkalinity and other major components to keep things balanced? While it makes sense to me to find a salt mix that mixes at your desired Alkalinity, I am struggling to find a highly regarded salt mix that mixes real-world around my desired 7.5-8dKH and can maintain that for a month in a mixing container for my auto-water change system.

My alternative is that I can run Kalk or 2-part to calculate and dose the offset but it feels like I would just be throwing away money by pulling out the Alkalinity that either dosed product is putting in. So how do I avoid this battle or better yet, how is everyone finding the balance here?

 

[radfly]

Hanna Alk is not accurate, due to reagent instability.

 

[jpark457]

If you are doing AWC and dosing, shouldn’t whatever happens from your AWC just be addressed as you dose for consumption? As in when you test you are tweaking and correcting whatever you dose, that should account for the AWC if anything more easily that a regular water change because the turnover is more gradual and closer to continuous.

 

[Waters]

You would have to change a lot of water to alter your ALK.....look at water changes as more of replenishing trace elements and removing nutrients as opposed to altering ALK.

 

[KStatefan]

If my salt mixes lower then i want it i just add baking soda to brig it up

 

[certain_code]

Hanna Alk is not accurate, due to reagent instability.

Where has this been discussed? I am not talking about chasing numbers here but testing daily with new reagent over a 3-week period with the same reagent would likely still identify trends, wouldn't it?

If you are doing AWC and dosing, shouldn’t whatever happens from your AWC just be addressed as you dose for consumption? As in when you test you are tweaking and correcting whatever you dose, that should account for the AWC if anything more easily that a regular water change because the turnover is more gradual and closer to continuous.

Agreed but to me, that dosing for consumption seems wasteful as the AWC is taking out what I am dosing to correct for. Yes, it's easy to calculate that dosage via regular testing and adjusting my alkalinity dosage accordingly. But in my case with a new tank I am trying to maintain 7.5 dKH and since my salt mixes closer to 6.5 dKH it feels really early to need to dose 2-part to maintain Alk with only a few frags in the system.

You would have to change a lot of water to alter your ALK.....look at water changes as more of replenishing trace elements and removing nutrients as opposed to altering ALK.

I'm not so sure about that. Previous comments may lead to investigating Hanna Alk Checker's accuracy but I see roughly a 0.5 dKH decrease in Alk a day when AWC is off but with it on I see closer to a 1 dKH drop at 6gal/wk changed in a 60gal system. Of course other factors could be at play but with only 4 1" SPS frags currently I dont see what else would warrant that sort of swing.

If my salt mixes lower then i want it i just add baking soda to brig it up

Does that help maintain Alk over time in a container? BRS did a test but it seems some salts drop in Alk faster than others so I am curious if baking soda would help keep elevated dKH over 30 days before my container is refilled again.

 

[Waters]

What is your total water volume and how much water are you changing per day?

 

[certain_code]

What is your total water volume and how much water are you changing per day?

Total water volume: 60gal
Per day water change: 5.4L or 1.43 gal

 

[jpark457]

You could correction dose whatever reservoir you use for the AWC- honestly probably not a huge if any difference doing that vs just dosing to maintain whatever you want in the main system. If you are discarding water from the display w the WC you are losing whatever you dosed no mater when you put it in.

 

[killer2001]

I'm auto changing 1 gallon a day in my 45gal. my alk will be in between 7.6 to 7.9 dKH and the alk of my saltwater reservoir is 8.6 to 9.0 dKH typically. I use red sea blue bucket 4 parts to 1 part of red sea black bucket... no dosing yet as I only have a few small coral frags. (@ 35ppt)

 

[certain_code]

I'm auto changing 1 gallon a day in my 45gal. my alk will be in between 7.6 to 7.9 dKH and the alk of my saltwater reservoir is 8.6 to 9.0 dKH typically. I use red sea blue bucket 4 parts to 1 part of red sea black bucket... no dosing yet as I only have a few small coral frags. (@ 35ppt)

So this is more of what I am trying to figure out. I want to avoid salt mixes with super high values but also avoid dosing until the AWC system cannot keep up with demand. So far both TM Pro and the Brightwell mixes have been lowering my Alk and making dosing 2part needed which just feels silly to keep doing long term

 

[Dburr1014]

So this is more of what I am trying to figure out. I want to avoid salt mixes with super high values but also avoid dosing until the AWC system cannot keep up with demand. So far both TM Pro and the Brightwell mixes have been lowering my Alk and making dosing 2part needed which just feels silly to keep doing long term

It seems you want 2 different things that are opposite.
A high alk salt will keep up with demand until the next day's water change. Our at least some of it.
I'm using IO at the moment at 1 gallon per day. It's at a high alk but run the tank at 8dkh. Of course the calrx keeps up the rest.

 

[KStatefan]

So this is more of what I am trying to figure out. I want to avoid salt mixes with super high values but also avoid dosing until the AWC system cannot keep up with demand. So far both TM Pro and the Brightwell mixes have been lowering my Alk and making dosing 2part needed which just feels silly to keep doing long term

If the AWC water is not above your target alk of the tank it can not keep up with demand.

You will either need to add alk to the awc water or switch to a different salt to keep up with demand or you can continue to use your current salt and supplement the tank with 2 part or kalk.

If you like your current salt i would continue to do what you are doing.

 

[Randy Holmes-Farley Verified Community Expert]

If you have reasonable demand for alk and calcium, then there should be no issues for an AWC if done slowly and frequently, no matter how far the salt mix deviates from the tank.

I used my AWC for a whole lot of slow changes each day totaling about 1% of the water volume daily. If the tank is 8 dKH and the salt mix is 11 dKH, then the water change just slowly and steadily adds 0.03 dKH per day.

IMO, an AWC is the best choice when using a salt mix that doesn't match the tank.

At the same time I did these changes, I was also adding alk and calcium using limewater (kalkwasser) to replace all evaporated water.