How often can I dose LC?

[clm65]

I recently tackled a high nitrate/high phosphate situation with carbon dosing. My nitrates are now around zero, and I’m working on getting them back up a little bit. But my phosphates are still high, around 0.3 - 0.5 ppm. They were up around 2.5 when I started, so a big improvement so far, but there is apparently so much bound up in my rocks that it is taking a while to get them down. I believe the nitrate/phosphate imbalance I have is the cause of a cyano problem I’m currently dealing with. So I’d like to get my numbers in order ASAP. I’ve been using Phosphate Rx about once per week. Can I safely dose it more frequently than once per week?

 

[GoVols]

Yep,
Bottomed out nitrates used to bring cyano my way too, and carbon dosing made it worse. Fuel

Can you stable out your nitrates and get your cyano gone first.

One thing at a time.

Most the time, ASAP leads to bad in an reef.

 

[clm65]

Yeah, I know...patience patience patience. And I'm trying to be patient. But the cyano has been present for a couple months and has been getting worse. Brushing, basting, and vacuuming is getting old. I started hydrogen peroxide dosing to combat it, but after 10 days so far it does not seem to be doing much. Plus I know I need to fix the underlying problem (the imbalance) in order to really keep it from coming back. So I would like to reduce the phosphates as quick as safety possible. Or at least get the level to a point that GFO can take over without being exhausted too quickly.

 

[Dkeller_nc]

From the chemistry standpoint, you can use lanthanum chloride as often as you want, as long as you still have significant phosphate in your water, and you're adding lanthanum chloride in the correct manner, which is drop-wise into a return from the tank that's fed into a felt filter sock. The reason you can get away with "as often as you want" is that lanthanum phosphate is almost completely insoluble in seawater, and the reaction between lanthanum ions and inorganic ortho-phosphate goes to completion - 100% of the lanthanum will be consumed as precipitated lanthanum phosphate.

However, you wouldn't want to overdose lanthanum chloride such that there's no phosphate to completely consume it. That's because one of the other compounds that can be formed from lanthanum ions in seawater is lanthanum carbonate. It's also completely insoluble, so an overdose of LaCl2 will drop the alkalinity in the water column.

From the biology aspect of this, if you have SPS in the tank, I'd advise you to stop removing phosphate by any means for a little while. SPS in particular definitely do not do well in tanks where they've been acclimated to high dissolved phosphate levels and then suddenly had that phosphate level drop precipitously. I'd most definitely not drop the phosphate to the 100 ppb range that's often cited for typical SPS tanks without acclimating the corals to the 500 ppb range for several weeks.

 

[clm65]

From the chemistry standpoint, you can use lanthanum chloride as often as you want, as long as you still have significant phosphate in your water, and you're adding lanthanum chloride in the correct manner, which is drop-wise into a return from the tank that's fed into a felt filter sock. The reason you can get away with "as often as you want" is that lanthanum phosphate is almost completely insoluble in seawater, and the reaction between lanthanum ions and inorganic ortho-phosphate goes to completion - 100% of the lanthanum will be consumed as precipitated lanthanum phosphate.

However, you wouldn't want to overdose lanthanum chloride such that there's no phosphate to completely consume it. That's because one of the other compounds that can be formed from lanthanum ions in seawater is lanthanum carbonate. It's also completely insoluble, so an overdose of LaCl2 will drop the alkalinity in the water column.

From the biology aspect of this, if you have SPS in the tank, I'd advise you to stop removing phosphate by any means for a little while. SPS in particular definitely do not do well in tanks where they've been acclimated to high dissolved phosphate levels and then suddenly had that phosphate level drop precipitously. I'd most definitely not drop the phosphate to the 100 ppb range that's often cited for typical SPS tanks without acclimating the corals to the 500 ppb range for several weeks.

Thank you! I am adding the LC to a gallon jug of RODI water and dripping it into a 10 micron sock in the sump, along with a drain line from the DT. And I only have a few zoas, some xenia, and gsp. No SPS. I think I'll increase the frequency to every 4 days and see how that goes.

 

[csb123]

I’ve been using LaCl daily for 2 months with ill effects of fish, lps, sps, or softies.

 

[clm65]

I’ve been using LaCl daily for 2 months with ill effects of fish, lps, sps, or softies.

Awesome info! What was your phosphate level when you started, and what is it at now? Are you just "maintaining" at this point, or are you still reducing the phosphate level?