Neptune Aquatics

Water change advice

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yngplo

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Hey all,

just wanted to kinda zone in on water change chemistry numbers as I grow my reef tank.

I'm interested in buying a dosing pump to keep my reef chemistry as consistent as possible, and lately, I've been getting away with weekly water changes for chemistry. At some point, this definitely can't be good for sensitive coral, assuming that there will be alkalinity jumps and (possibly) calcium or other nutrient jumps, right?

After testing earlier today and two days ago at the same time, I saw my alkalinity drop from 8.6 dkh to 8.4, and my calcium has stayed consistent at 460.

How should I go about water changes to make sure that my coral won't suffer from chemistry jumps? I have a IM 40 AIO, and I change 5 gallons weekly.

Thanks!
 
So one caveat to purchasing a dosing pump to keep parameters consistent: frequent testing is important because your tank's nutrient usage changes over time (and, under some circumstances, can change pretty radically) due to coral growth and general tank 'happiness.' For example: prior moving my 20 gallon tank, it was using ~0.8-0.9 dkh/day of alkalinity. After moving it, the first week it only used ~0.3-0.4 dkh/day. Four days later it jumped suddenly to 0.7 dkh/day. Then it slowly built back up to 0.8-0.9 dkh/day over the next couple weeks.

Regarding water changes to avoid chemistry jumps: there are a couple ways to approach this. My strategy was to do daily dosing of alkalinity and calcium to keep my target parameters (~8.5 dkh, 450 ppm Ca) on a day-to-day basis, and then attempt to match salinity/alkalinity/calcium on the new water. Given many salt mixes give high alkalinity (ex: I think Instant Ocean regular is 10 or 11 dkh when mixed fresh, IO Reef Crystals is ~13), I'll typically let it mix for a couple days to bring the alkalinity down a bit.

While keeping parameters stable is important, I would also say that chasing perfect numbers is just that...numbers. Use your tank as a guide and see how happy your corals are to see if your routine is good enough. I'm somewhat lazy and don't want to dose several times per day, so I'll usually dose alkalinity and calcium once per day...which involves a swing of ~0.8-0.9 dkh/~8 ppm calcium over the course of ~4-5 minutes. My philosophy is that coral reefs undergo fluctuations in salinity, light, pH, etc. on a daily basis, so it's not disastrous to do in a tank. So far everything I have is happy and growing well, but data point of one person (and I've only been in the hobby ~8 months) so I'd let others chime in as well.

Edit: Also, important math to note: alkalinity and calcium are used in roughly the same ratio (barring weird circumstances). 2.8 dkh = 20 ppm of calcium, so you can use that math to fine tune your dosing (if you choose to go that route).
 
I noticed in another thread you want to add a clam. You will not be able to sustain the Alk/Ca needs of a clam with water changes alone, you will absolutely need to dose and closely monitor (check Alk every day or 2 at least at the start). They consume a LOT of Alk when they are growing. They need high SPS level lighting. Clams in newish tanks with new reefers usually die from what I’ve seen.

And you are correct that big jumps in Alk up or down with water changes is not consistent with success in the more sensitive corals like SPS.

Contrary to advice I see a lot online, I think new reefers should chase numbers, to a point. Obviously I‘m not saying you should tweak continuously to get to the last decimal point. But it takes years of experience to catch problems caused by out of whack parameters early by just looking at your tank, if it ever is really possible. I think a huge proportion of the booming success of the hobby in the last several years is because parameters are easier to measure and easier to know what to do with.
 
Last edited:
JVU said:
I noticed in another thread you want to add a clam. You will not be able to sustain the Alk/Ca needs of a clam with water changes alone, you will absolutely need to dose and closely monitor (check Alk every day or 2 at least at the start). They consume a LOT of Alk when they are growing. They need high SPS level lighting. Clams in newish tanks with new reefers usually die from what I’ve seen.

And you are correct that big jumps in Alk up or down with water changes is not consistent with success in the more sensitive corals like SPS.

Contrary to advice I see a lot online, I think new reefers should chase numbers, to a point. Obviously I‘m not saying you should tweak continuously to get to the last decimal point. But takes years of experience to catch problems caused by out of whack parameters early by just looking at your tank, if it ever is really possible. I think a huge proportion of the booming success of the hobby in the last several years is because parameters are easier to measure and easier to know what to do with.
Click to expand...

Thanks for the advice!

Yeah, I heard clams were pretty difficult to keep at first, that’s why I really wanna get better at testing and understanding the numbers that will go into providing a tank for one.

I currently use a maxspect razor on my tank, would that suffice the sps-style lighting a clam would need?

At the moment I’m testing once every two days, and when I get the numbers right, I’ll be using a dosing pump accordingly.


Sent from my iPhone using Tapatalk
 
yngplo said:
Thanks for the advice!

Yeah, I heard clams were pretty difficult to keep at first, that’s why I really wanna get better at testing and understanding the numbers that will go into providing a tank for one.

I currently use a maxspect razor on my tank, would that suffice the sps-style lighting a clam would need?

At the moment I’m testing once every two days, and when I get the numbers right, I’ll be using a dosing pump accordingly.


Sent from my iPhone using Tapatalk
Click to expand...

I don't know anything about that specific light, but - if you're interested in lighting levels in your tank - you can borrow one of the club's photosynthetically active radiation (PAR) meters to get a better idea of the lighting levels in your tank. This will help you figure out if you have the right amount of light where you want to put it, and can also help you better tune your lighting levels for your livestock.
 
yngplo said:
Thanks for the advice!

Yeah, I heard clams were pretty difficult to keep at first, that’s why I really wanna get better at testing and understanding the numbers that will go into providing a tank for one.

I currently use a maxspect razor on my tank, would that suffice the sps-style lighting a clam would need?

At the moment I’m testing once every two days, and when I get the numbers right, I’ll be using a dosing pump accordingly.


Sent from my iPhone using Tapatalk
Click to expand...
In my opinion, you would want to test PAR in your tank before adding difficult SPS or a clam to see if and where the light is sufficient. I would not rely on type of light, estimates on what has worked for others, or how it looks personally. We have PAR meters to borrow in the club.
 
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