More kalk with AWC instead of vinegar

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SteveWin1

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I haven't seen this discussed, but maybe I'm just bad at searching. Bear with me... So if you're using limewater/kalkwasser/calcium hydroxide for your alkalinity and calcium, it helps raise the pH and is cheaper than using 2 part. The main complaint about it that I've seen (besides the possibility of nuking your tank if you don't have it set up properly and don't have safeguards) is that eventually your need for alkalinity will be higher than the amount of saturated limewater you can add to replace evaporated water. A common solution to this is to add vinegar to the kalkwasser reservoir to increase the solubility and get more alkalinity and calcium per volume of limewater. The downside to doing this is that you lose some of the pH boost and you're adding carbon to your tank, which you may not want. Plus there's one more thing you have to buy and measure out (vinegar). A lot of us have an AWC system, which seems to provide the perfect solution. If you've got a AWC system set up, you probably already check your salinity fairly regularly. If your salinity is high, you can just drop the amount of new saltwater coming in and your ATO will slowly dilute out the salt. If your salinity is too low, you can add new saltwater a little quicker and your ATO will automatically slow down which slowly concentrates your water. The problem with adding more kalk than your evaporation rate is that your salinity would drop and your sump would overflow. But, if you've got an AWC system running, you could pull enough extra water out to match the extra kalk you're adding. The only problem would be that your salinity would slowly drop. If you mix up your new saltwater to be more concentrated than your display tank, though, you need less volume of new saltwater to replace the salt you are removing through the AWC system to make room for the extra kalk. Hopefully that all makes sense. That's what I'm doing now and it seems to be working. Just haven't seen anyone mention that this is an option anywhere. At some point, I assume the saltwater in my brute trashcan would have to be so concentrated that stuff would precipitate out, so there's still probably a limit, but this definitely seems to be a way to stick with kalk for longer without having to mess with vinegar and without getting more dosing pumps to start using 2-part.
 
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RobB'z Reef

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I haven't seen this discussed, but maybe I'm just bad at searching. Bear with me... So if you're using limewater/kalkwasser/calcium hydroxide for your alkalinity and calcium, it helps raise the pH and is cheaper than using 2 part. The main complaint about it that I've seen (besides the possibility of nuking your tank if you don't have it set up properly and don't have safeguards) is that eventually your need for alkalinity will be higher than the amount of saturated limewater you can add to replace evaporated water. A common solution to this is to add vinegar to the kalkwasser reservoir to increase the solubility and get more alkalinity and calcium per volume of limewater. The downside to doing this is that you lose some of the pH boost and you're adding carbon to your tank, which you may not want. Plus there's one more thing you have to buy and measure out (vinegar). A lot of us have an AWC system, which seems to provide the perfect solution. If you've got a AWC system set up, you probably already check your salinity fairly regularly. If your salinity is high, you can just drop the amount of new saltwater coming in and your ATO will slowly dilute out the salt. If your salinity is too low, you can add new saltwater a little quicker and your ATO will automatically slow down which slowly concentrates your water. The problem with adding more kalk than your evaporation rate is that your salinity would drop and your sump would overflow. But, if you've got an AWC system running, you could pull enough extra water out to match the extra kalk you're adding. The only problem would be that your salinity would slowly drop. If you mix up your new saltwater to be more concentrated than your display tank, though, you need less volume of new saltwater to replace the salt you are removing through the AWC system to make room for the extra kalk. Hopefully that all makes sense. That's what I'm doing now and it seems to be working. Just haven't seen anyone mention that this is an option anywhere. At some point, I assume the saltwater in my brute trashcan would have to be so concentrated that stuff would precipitate out, so there's still probably a limit, but this definitely seems to be a way to stick with kalk for longer without having to mess with vinegar and without getting more dosing pumps to start using 2-part.
Like most problems waiting to be solved there are multiple solutions to choose from. Everything has pros and cons. I'm of the opinion, the more complexity you introduce into a solution the more apt it is to fail and manage. While what you're doing probably works at some level for you isn't going to be viable for most ppl. Anything ppl dose in their tasks has a probability of failing and nuking their tank. Kalkwasser isn't inherently more or less likely to trash your tank than any two part additive that goes haywire.

When your alk demands exceed the evaporation rate of your tank that a normalized solution of calcium hydroxide can accommodate their is a more simple solution to handling it. Dose a kalkwasser slurry. It's what several of us out there are doing and it's proven to work and it's not complex at all. It has no more or less failure points than any other given dosing solution has with perhaps one exception. It can be a little hard on the mixing pump but that's been solved as well. Just create a 3-4% by weight solution of calcium hydroxide with rodi water and keep it in suspension.

You then dose the kalkwasser that's in suspension (note, it's not dissolved) to the tank as intermittently as possible based on your demand. At 4% the strength is 24x that of a normal solution (1.73g/L is normal solution). In some respects, the analogy could be used that you're using the system volume of water in your tank as a kalk reactor. This isn't literally true but maybe it helps visualize. You have to dose into a very high flow area to avoid abiotic precipitation but there are options for this. A power head in your sump (what I do) or even straight down the main or secondary drain of your overflow (I've tested this as well).

This isn't a method for normal alk demands, only when you want a simple balanced additive (Ca & Alk) and keep the solution super cheap. Buy food grade Mississippi lime in 50# bags and it's ten times cheaper yet over any two part. I calculated it costs me .06 cents per dkh on my 200 gallon system.
 
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SteveWin1

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Hey, thumbs up for being a pioneer but keeping things balanced your way seems alot more difficult than just dosing some two part.
Why would it be difficult to keep things balanced?

Lets say you normally mix up new salt by putting 20 cups of salt in your 40 gallon brute trash can. Lets say your AWC goes fast enough to drain the trash can every month, at which point you mix up new saltwater. Lets say your corals have grown to the point that your ATO never runs because you're adding enough limewater to completely make up for evaporation. Despite this your alk is slowly dropping and you have to do something...

What I'm suggesting is, next time you mix up saltwater, put 5 extra cups of salt in there and then slow the AWC head that adds water to your tank by 20% to exactly compensate for the higher concentration in your brute. That's literally it. Now you can add up to 2 gallons of extra limewater per week. Your salinity will remain stable, because your ATO will compensate for the lower volume of water being added just like it would compensate for additional evaporation. The water in your brute will also last you more than a week extra, so you'll spend less of your life mixing saltwater and your AWC system will spend less time being down and waiting for the salt to finish mixing. The amount of salt you'll go through in a month is exactly the same, so there's no extra cost. You'll have 20% less wear on the head that sends saltwater to your aquarium (yes, more on your ATO/kalk pumps, but if you simply increased evaporation with a fan or something, that would be the case anyway, without the 20% savings on AWC add speed).

This is just an example. You could adjust the salt concentration for whatever your kalk needs are (until you start getting precipitation in your mixing station). Definitely not a solution for everyone, but if you're already doing kalk and have AWC and ATO, it'll keep you going longer without investing in more pumps, more containers, running more lines into your sump and having to stock and mix up 2 part.
 
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