derek_SR
Supporting Member
DISCLAIMER: I am not a chemist, just a well-read hobbyist at best. Your experience and/or results may not be the same as what I describe here. Go slowly, pay attention to your tank, and know that there are always risks.
This topic seems to come up often enough, so rather than reference people to my tank journal all the time I figured I'd just write a brief guide. Rich Ross used this same method to lower his phosphates over an extended period of time and discussed it during an episode of Reef Beef (if anyone can tell me which - I'll update this with the specific episode). The Steinhart aquarium also uses it to control Po4, as do several other BAR members.
Side note #1: It's commonly believed that live rock "binds" phosphate, or "soaks it up" - equalizing with the level in the water over time. This means that as you lower the po4 level in your water, your rocks will leech some of what they have back into it - making it difficult to get them down, or even making it seem like lowering them isn't working at all. I can't speak to the science behind this or whether it is true or not, but it was 100% the experience I had. My Po4 was in the .75 range when I started, and I had to dose LaCl very heavily for several months while slowly tapering off the dose before it finally levelled out at my 0.15 target. Just FYI. While annoying when trying to make meaningful adjustments to your target, it acts a nice buffer once you're there to keep things stable.
Pros of LaCl dosing:
Cons of LaCl dosing:
The skimmer method:
I am personally using the skimmer method - and have progressed from 200ml/day of this 1:100 dilution initially (when I had very heavy po4 and my rocks were leeching it) down to just 5ml/day where I am currently to maintain my target of 0.15 phosphate. This equates to just 0.05ml of the actual LaCl product per day - a TINY amount needed to maintain my po4, and I feed HEAVILY and use no mechanical filtration. I see no lanthanum on my Triton ICP results.
Alternative methods:
Side note #2: As noted earlier, LaCl binds almost immediately to po4 - forming an inert solid. This particulate is not harmful, but it can settle in your sump over time if not skimmed out or filtered out. As your po4 starts approaching zero, though, the "unbound" raw LaCl can stay in the water column for longer periods of time looking for po4 - and one must be very careful when dosing it to very low levels of Po4. This, and/or dosing large quantities at once, is where the risk to your Yellow Tang comes in. Raw LaCl in the water can (anecdotally) be toxic to these fish, and will even show up on ICP. Go slow and keep it diluted! If you are targeting very low levels of po4, I recommend backing off of LaCl entirely lower than about 0.05 po4, which keeps you on the safe side of zero and beyond the error range of most test kits.
LaCl Products specifically for reef aquarium use:
Happy Reefing!
This topic seems to come up often enough, so rather than reference people to my tank journal all the time I figured I'd just write a brief guide. Rich Ross used this same method to lower his phosphates over an extended period of time and discussed it during an episode of Reef Beef (if anyone can tell me which - I'll update this with the specific episode). The Steinhart aquarium also uses it to control Po4, as do several other BAR members.
Side note #1: It's commonly believed that live rock "binds" phosphate, or "soaks it up" - equalizing with the level in the water over time. This means that as you lower the po4 level in your water, your rocks will leech some of what they have back into it - making it difficult to get them down, or even making it seem like lowering them isn't working at all. I can't speak to the science behind this or whether it is true or not, but it was 100% the experience I had. My Po4 was in the .75 range when I started, and I had to dose LaCl very heavily for several months while slowly tapering off the dose before it finally levelled out at my 0.15 target. Just FYI. While annoying when trying to make meaningful adjustments to your target, it acts a nice buffer once you're there to keep things stable.
Pros of LaCl dosing:
- Very cheap
- Low maintenance - no reactors to clean, nothing to change. One batch in a 2L dosing container lasts 13 months @ 5ml/day
- Predictable and reliable - dosing precise quantities of a diluted solution makes it very easy to tune, compared with something like GFO
- minimal impact to your water chemistry other than Po4 - it can lower alk slightly when bolus dosed, but this is not noticeable when slow dosing (in my experience)
Cons of LaCl dosing:
- you need a dedicated dosing pump - especially if using the skimmer method (it CAN be dosed by hand, though, see below)
- it is known to kill yellow tangs specifically (no idea why this is) if a significant quantity of unbound LaCl escapes into your tank - see side note #2
The skimmer method:
- Mix up a diluted batch of LaCl solution - I use a 1:100 dilution, and mix 15ml of LaCl into about 1500ml of RODI. It doesn't have to be diluted, but it makes it much safer and gives you some wiggle room as you dial in the dose. There's a handy calculator here, depending on the product you are using: http://larryl.emailplus.org.user.fm/fish/dosing-instructions-phosphate-removers.html
- Use the calculator above to identify your starting dose (I link to some common products at the end of this post) - targeting a specific daily po4 adjustment (e.g. - lower po4 by 0.1 per day). Given my side note above, you may be able to go with significantly larger doses initially if you find your rocks are leeching a lot of po4.
- I recommend dosing slowly over time - especially as your Po4 gets lower, giving the LaCl time to bind with the phosphates in the skimmer body and get skimmed out. "Continuous duty" dosers are ideal, the Versa is a good example (and what I have used for some time).
- Run a silicone dosing tube from the LaCl pump directly down into the body of your skimmer, like so:
The LaCl binds with the Po4 in the water inside the skimmer body - forming an inert particulate that gets skimmed out. Other ways to get it into your skimmer: 1. Dropper by hand, directly into the air inlet or skimmer body. 2. Dosed directly in front of the water pump intake 3. some skimmers have an ozone inlet (Reef Octo) and it can be dosed there. Note that you should inspect your pump periodically if dosing upstream of it.I am personally using the skimmer method - and have progressed from 200ml/day of this 1:100 dilution initially (when I had very heavy po4 and my rocks were leeching it) down to just 5ml/day where I am currently to maintain my target of 0.15 phosphate. This equates to just 0.05ml of the actual LaCl product per day - a TINY amount needed to maintain my po4, and I feed HEAVILY and use no mechanical filtration. I see no lanthanum on my Triton ICP results.
Alternative methods:
Filter Sock - You can dose LaCl into a filter sock in your sump. It should be a 25-50micron sock (or smaller). You should still go slowly, as any unbound LaCl will pass through the sock and into the water column. Skimmer is much preferred, but if you are only dosing LaCl occasionally a filter sock could be easier. Note that it will clog fairly quickly so stay on top of it.
Overflow and pray - Some people just dose LaCl directly into their overflow by hand, skipping the doser. I would only do this if you have fairly high po4, so that it all "binds" before making its way back up into the DT. The instructions on some of the LaCl products actually suggest doing this - so it's fairly safe, but see side note #2 below.
Side note #2: As noted earlier, LaCl binds almost immediately to po4 - forming an inert solid. This particulate is not harmful, but it can settle in your sump over time if not skimmed out or filtered out. As your po4 starts approaching zero, though, the "unbound" raw LaCl can stay in the water column for longer periods of time looking for po4 - and one must be very careful when dosing it to very low levels of Po4. This, and/or dosing large quantities at once, is where the risk to your Yellow Tang comes in. Raw LaCl in the water can (anecdotally) be toxic to these fish, and will even show up on ICP. Go slow and keep it diluted! If you are targeting very low levels of po4, I recommend backing off of LaCl entirely lower than about 0.05 po4, which keeps you on the safe side of zero and beyond the error range of most test kits.
LaCl Products specifically for reef aquarium use:
Brightwell Phosphate-E: https://www.saltwateraquarium.com/p...axqrmbHi5GhPaRugCO3mCbzyNjCZ58FwaAjXBEALw_wcB
Two Little Fishes Phosban - L: https://www.saltwateraquarium.com/l...HXrnFc2feQEZOVP4qcGJiQjhgin3xrNoaAlcQEALw_wcB
**You can also use generic LaCl for lowering phosphate in pools - this is the cheapest route of all, but I would do further research to be confident in the purity of the product. Given how little of the stuff is required once your po4 is stabilized, I don't think the cost savings is worth it - even the name brand reef products are dirt cheap over time.
Side note #3: My intention is not for this guide to provide any perspective on WHERE you target your Po4 level, or to debate the merits of high vs low. I chose 0.15 simply as a number high enough to not worry about accidentally ever hitting zero. I also did not want my Po4 to raise forever - so I picked that target somewhat arbitrarily. I believe you can have a successful system at a wide range of Po4 levels - this is simply a tool to maintain it where you want it.Happy Reefing!
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