Starting 2 Part for the first time; need some guidance

[Phyber]

Hi all! I am in about month 5 of my second venture into reefing and my tank is doing great so far. I've been religious with biweekly 25% water changes with RC salt set at 1.026. I have also been doing repetitive testing for Alk/Cal/Mag. I ordered the 2 part starter kit and have some questions before I use...

I have been pretty stable with Alk, but I saw a 1 dkh drop in a week after adding a clam and a few frags. I did a water change and saw a .8 dkh increase from my salt. How should I compensate for this with my 2 part? I would like to hold at ~9.9 dkh, but if every two weeks I'm adding in .8, then won't I just keep upping the levels or should i start making a less "potent" salt mix for my changes? If this last water change pattern holds true, and weekly I lose 1 dkh but my salt mix replaces .8 dkh, I can't keep up with the water changes (my bi weekly would be spaced out too long and my weekly changes aren't logistical with my schedule and RODI unit) and I need to start using 2 part?

For Mag, the BRS Tv videos say to just dose 20ml after you're done with a gallon each of Alk and Cal... is that it? I don't dose Mag in the meantime with the Alk/Cal, and it's just a 20ml drop in the sump or etc?

 

[muzikalmatt]

Ideally if you're going to start dosing you'll want to use a salt mix that closely matches your desired water parameters, that way you don't have to worry about water changes affecting your dosing regimen, especially if you're using dosing pumps.

I've been dosing BRS 2-part by hand and I use Reef Crystals as well. I simply don't dose on the day I do a water change as it essentially has the same effect as dosing due to the elevated parameters. However, if your water changes elevate your parameters more than your daily consumption, this may not work for you as you'll be steadily increasing your overall levels rather than just maintaining them.

You could try switching salts to something closer to your goal parameters, or reduce the amount of water you change to reduce the effect on your parameters, or you could try letting the freshly mixed water sit a day or two prior to a water change to let the alkalinity drop. Reef Crystals tends to reduce alkalinity over time so that might work. However, I'm not sure if that affects the overall chemistry of the water or not. I'm certainly no expert.

Regarding Magnesium, according the the BRS 2-part How To video once you deplete the both full gallons Alkalinity and Calcium you're supposed to dose 20 ounces (2.5 cups) of Magnesium (not 20 milliliters). However, you may not need to do that as Reef Crystals has elevated Magnesium levels as well. I certainly don't think I would dose that much without testing first.

Here are a couple of calculators that I've found helpful for dialing in dosing and water change effects.

Effect of Water Change Calculator - This one's great for determining how a water change will effect any parameter. I used it to see how my water changes would affect alkalinity based on my tank volume, water change volume, current alk levels and the fresh saltwater alk levels. I was able to determine that a 5 gallon water change with Reef Crystals essentially had the same effect as daily dosing for my tank.

BRS Reef Calculator - Since you're starting 2-part you probably already know about this one, but just in case, this is the go-to for determining how much you need to dose. Dosing is a moving target as your corals grow and you add things like clams that have a higher alk/calc demand, so be sure to check your levels every so often once you start dosing. I tested daily for the first week or so to make sure everything was staying stable.

Hopefully this gives you some direction and potential options for moving forward. Obviously the goal with dosing is stability so you don't want to defeat the purpose by doubling up with dosing and water changes with elevated parameters. I'm certainly no expert and haven't been dosing for all that long, but I've definitely found the tank to be much happier since I started.

 

[Phyber]

Thanks for that info! So, despite my 1 dkh swing over 7 days, am I just not at a point where I need to start dosing yet? My goal is stability and I will eventually be getting a dosing pump...but the math says that I'm losing 0.15 dkh per day.

To me, that means my biweekly water change schedule will have the tank drop 2 dkh, and only be able to up it .8 dkh. My Cal went up 5 ppm and my Mag went up 10 ppm. Does that mean I need to factor a 1.2 dkh drop between water changes and dose for that? I'd just unplug the dosing pump on water change day?

 

[muzikalmatt]

While losing 1 dKH over a week's time isn't a huge drop, if you're only doing bi-weekly water changes that raise your dKH by 0.8 you would probably benefit from dosing because eventually you're just going to fall behind on your levels.

As you suggested you could reduce your dosing so that your alkalinity is slowly dropping over two weeks' time such that you're only down 0.8 dKH on water change day. That means you just need to make up the other 1.2 dKH with dosing. If you spread it out over 14 days, you'd need to dose to raise your alkalinity ~0.08 dKH per day. That way on water change day you're bumped back up to your target of 9.9 dKH.

Honestly this is an overly complicated approach which is why getting a salt that's closer to your ideal parameters is probably a better idea. That way you can just maintain a steady dosing regimen and you will have the most stability possible.

Hopefully someone else can chime in with some better advice on how to handle this situation as I'd hate to steer you in the wrong direction.

 

[Phyber]

Thanks again! I'm not 100% sure what you mean by a salt with ideal parameters...I'm guessing the RC is set for elevated levels compared to natural saltwater, but if I wanted to keep higher levels wouldn't I just have to compensate by dosing more?

Prior to my recent coral additions, all levels were holding steady. I understand levels will drop as my coral population grows, but if I'm dosing correctly for the amount of loss i'm seeing in my tests (ie my .15 dkh daily drop average) won't the new water from the water change just keep it up to the same 9.9 level?

 

[muzikalmatt]

What I mean by ideal parameters is the parameters/levels you are trying to maintain in your tank. Since you want to maintain 9.9 dKH it would be ideal if you can find a salt that mixes at ~10 dKH. You'll want similar calcium/magnesium levels as well but it's most important to match alkalinity. I think Tropic Marin's regular salt (not the Pro version) mixes around 10 dKH so that might be an option.

This way when you do a water change, you're not affecting your major elements (alk/calc/mag) at all. With this method your water changes are mainly for reducing nitrates/phosphates and replenishing trace elements and your 2-part dosing handles alkalinity and calcium.

 

[Phyber]

Which is what I think I'm seeing now...? This RC, with minimal corals prior (a few LPS and zoas) was holding steady with 9.9 Alk/ 490 Cal/ 1410 Mag...then it started dropping as I see coraline coming on and adding my clam and sps.

I'm going to stick with RC salt (price and availability) so I'm happy with it being the levels it is, I just am trying to get a broader picture of how to incorporate a water change routine with dosing, as I've never dosed before.

 

[muzikalmatt]

That sounds like a good plan. I had similar issues with my tank as the coralline algae growth started to really consume alkalinity. I've been slowly upping my alkalinity over time, but I'm trying not to chase a specific number as the tank seems happy around the 8.0 dKH mark. So I just dose to try and maintain that level daily.

Best of luck to you and I hope the information I provided was helpful.

By the way, I just noticed you're located in Danville, VA. I'm in Roanoke! Great to see another local hobbyist on the forums here! You should check out the SWVA Reef Club sub-forum. I've been trying to drum up more activity over there so we could maybe get some frag swaps going in the future.

 

[Phyber]

I'll give it a shot in that sub! I'm about as close to Greensboro NC as I am Lynchburg, with Roanoke being even further but I would like to meet up with some "locals"!

 

[Bulk Reef Supply]

Ideally if you're going to start dosing you'll want to use a salt mix that closely matches your desired water parameters, that way you don't have to worry about water changes affecting your dosing regimen, especially if you're using dosing pumps.

I've been dosing BRS 2-part by hand and I use Reef Crystals as well. I simply don't dose on the day I do a water change as it essentially has the same effect as dosing due to the elevated parameters. However, if your water changes elevate your parameters more than your daily consumption, this may not work for you as you'll be steadily increasing your overall levels rather than just maintaining them.

You could try switching salts to something closer to your goal parameters, or reduce the amount of water you change to reduce the effect on your parameters, or you could try letting the freshly mixed water sit a day or two prior to a water change to let the alkalinity drop. Reef Crystals tends to reduce alkalinity over time so that might work. However, I'm not sure if that affects the overall chemistry of the water or not. I'm certainly no expert.

Regarding Magnesium, according the the BRS 2-part How To video once you deplete the both full gallons Alkalinity and Calcium you're supposed to dose 20 ounces (2.5 cups) of Magnesium (not 20 milliliters). However, you may not need to do that as Reef Crystals has elevated Magnesium levels as well. I certainly don't think I would dose that much without testing first.

Here are a couple of calculators that I've found helpful for dialing in dosing and water change effects.

Effect of Water Change Calculator - This one's great for determining how a water change will effect any parameter. I used it to see how my water changes would affect alkalinity based on my tank volume, water change volume, current alk levels and the fresh saltwater alk levels. I was able to determine that a 5 gallon water change with Reef Crystals essentially had the same effect as daily dosing for my tank.

BRS Reef Calculator - Since you're starting 2-part you probably already know about this one, but just in case, this is the go-to for determining how much you need to dose. Dosing is a moving target as your corals grow and you add things like clams that have a higher alk/calc demand, so be sure to check your levels every so often once you start dosing. I tested daily for the first week or so to make sure everything was staying stable.

Hopefully this gives you some direction and potential options for moving forward. Obviously the goal with dosing is stability so you don't want to defeat the purpose by doubling up with dosing and water changes with elevated parameters. I'm certainly no expert and haven't been dosing for all that long, but I've definitely found the tank to be much happier since I started.

This is all great advice! Starting out with a salt mix that mixes up to the same major elements (alkalinity, calcium, and magnesium) as your tank will help out tremendously.