remote deep sand bed for no3/po4

Court_Appointed_Hypeman · Nov 8, 2023

Over the top for the deep sand bed makes perfect sence. If you force water through it, it will just make the sand aerobic.

Over the top will allow the nutrients to continue to reduce in concentration as its used up in the sand bed.

Carbon dosing does take a while to start. The bacteria populations have to adjust and build up

A lot of the changes you have made probably have a huge lag time to show up simply because the microbiome battlefield shifts.

I am excited to see how the sandbed works out, it's going to take a few montha I assume.

Also, I am still new to the hobby 1 year in just throwing my 2 cents in

Gtinnel · Nov 8, 2023

Court_Appointed_Hypeman said:
Over the top for the deep sand bed makes perfect sence. If you force water through it, it will just make the sand aerobic.

That’s mostly true, but if you can control the flow to slow down how much water goes through the sand (media) then most of it can still be anaerobic.

jda · Nov 8, 2023

davidwillis said:
I have added 3 5 gallon buckets of sand, and plan on changing out one bucket every year, so they will not be in use more than 3 years before changed or cleaned.

How far did you fill up the buckets in inches? I am just curious.

Of course anoxic bacteria grow where there is no oxygen... and these bacteria get oxygen from the no3 molecule and make n2. Science. I guess that this is the dreaded old-science since along with cyanobacteria had a huge impact on making the earth what it is today.

Back in the day, people who used sealed containers sometimes had to use vents to let N gas escape. Sometimes not.

Calfo gets into it here about twenty years ago:

DSB in a bucket for nitrate control - Reef Central Online Community

DSB in a bucket for nitrate control Advanced Topics

www.reefcentral.com

Dr. Ron has talked about this a lot (his website looks to be out of commission):

Wet Web Media has many topics about this - Fenner, Lorenzo and Andrew answer 7 LONG pages of FAQs - just search from "denitri" and skip to the right parts. WWM is hard to read, but the knowledge there is amazing if you slog through:

https://www.wetwebmedia.com/dsbfaqs.htm

My experience always has been that the DSBs of any type (remote or in tank), will get to a level and then get steady. More and deeper sand can get to .1, or so - this is where mine sits. I have a FOWLR where I feed EXCESSIVELY and the sand is only about 2 inches and it stops at 2-3 ppm - more sand would likely lower this, but the fish move it around and I don't care to add more.

Remember that the aragonite will bind phosphate en masse. If you don't otherwise handle phosphate, it could start to rise as the new aragonite starts to "fill up." With a remote DSB, you can just replace the sand, but still a good idea to keep this in mind.

jda · Nov 8, 2023

I did not say this very well above, but there is no known way for anoxic bacteria to take nitrate to true zero. The biology and mechanics don't seem to allow it. The no3 can get low which might look like zero on a hobby-grade test kit, though.

jda · Nov 8, 2023

If anybody thinks that things go into the sand to rot and then leech back out nasty things into the reef, then they don't understand the biology or science here. Just like every other ecosystem, there is nothing of value that goes unused. The oxic (top) layer of the sand will have enough bacteria and micro organisms in it to quickly take care of any organic materials that enters - very fast. We have all see how quickly a whole fish can get turned into nothing in a reef tank and the sand has even more bacteria, protozoans and stuff than the water column does.

The grey gunk that settles in the sand, and sump, is inert. It is nasty and can gum up the works and not allow water to flow through the sand as well, but it does not have any nutritional value or else it would have been used up already - this is the same stuff that many folks have in their sumps that does not matter either. This is one thing that I think that Dr. Ron got wrong - this inert gunk needs to be removed. This is simple in remote DSB - just remove it, clean it or replace the sand. In the tank, I vacuum small sections of the sand starting in about year 4 and trying not to do more than 20-25% every few months to allow the oxic and anoxic zones to re-establish. In the tank, if you slowly do this work, your tank will not notice at all. Since you mixed the anoxic and oxic areas, you will have some bacterial death, so your tank has to absorb this too.

In the tank, you also have to add new sand. These lower pH anoxic zones can dissolve sand. This is normal. Washed sand down a 2-3" PVC pipe in shallow (like 1/2 inch) amounts at a time is no problem. You don't want to bury your good sand critters in a tank. In a remote DSB, you can just shore this up when you replace/wash/whatever your sand.

Beefyreefy · Nov 8, 2023

So I agree with a few other people here and think you should keep things simple. Big skimmer, water changes, filter socks. You’ve got a lot going on here. I’ve always had high nutrients and once the biomass of coral starts growing the algae’s and uglies just sort themselves out. I think there’s more to the story are why your corals died, personally trace element depletions is the least likely reason IMO. I’ve found that carbon dosing, bio pellets, chemical treatments all just create new issues. That being said ymmv and just when I have things figured out things go south lol.

jda · Nov 8, 2023

Lastly, for now, I like to have a sand bed to chew through waste products, like nitrate, so that I can feed a massive amount of food to get actually available sources of nitrogen to my corals in the form of ammonium from the fish. I can feed as much as I want and nitrate stays in a good place. Other phosphorous forms from the fish waste is better than po4 too, but this is harder to handle and requires to grow a LOT of chaeto, but orthophosphate as a waste product is another topic for another thread...

davidwillis · Nov 8, 2023

jda said:
How far did you fill up the buckets in inches? I am just curious.

Of course anoxic bacteria grow where there is no oxygen... and these bacteria get oxygen from the no3 molecule and make n2. Science. I guess that this is the dreaded old-science since along with cyanobacteria had a huge impact on making the earth what it is today.

Back in the day, people who used sealed containers sometimes had to use vents to let N gas escape. Sometimes not.

Calfo gets into it here about twenty years ago:

DSB in a bucket for nitrate control - Reef Central Online Community

DSB in a bucket for nitrate control Advanced Topics

www.reefcentral.com

Dr. Ron has talked about this a lot (his website looks to be out of commission):

Wet Web Media has many topics about this - Fenner, Lorenzo and Andrew answer 7 LONG pages of FAQs - just search from "denitri" and skip to the right parts. WWM is hard to read, but the knowledge there is amazing if you slog through:

https://www.wetwebmedia.com/dsbfaqs.htm

My experience always has been that the DSBs of any type (remote or in tank), will get to a level and then get steady. More and deeper sand can get to .1, or so - this is where mine sits. I have a FOWLR where I feed EXCESSIVELY and the sand is only about 2 inches and it stops at 2-3 ppm - more sand would likely lower this, but the fish move it around and I don't care to add more.

Remember that the aragonite will bind phosphate en masse. If you don't otherwise handle phosphate, it could start to rise as the new aragonite starts to "fill up." With a remote DSB, you can just replace the sand, but still a good idea to keep this in mind.

Thanks for all that information. I have read through the 20 year old reef central thread. I will also look through the others.

Each bucket has about 12" of sand.

I think it is good that it does not take it all the way to zero (we need some no3).

I am using phosban-l (in a reactor, then through a 5 micron filter) to keep po4 down. Current level is 0.09, but I can easily adjust it by changing my dosing.

davidwillis · Nov 8, 2023

Beefyreefy said:
So I agree with a few other people here and think you should keep things simple. Big skimmer, water changes, filter socks. You’ve got a lot going on here. I’ve always had high nutrients and once the biomass of coral starts growing the algae’s and uglies just sort themselves out. I think there’s more to the story are why your corals died, personally trace element depletions is the least likely reason IMO. I’ve found that carbon dosing, bio pellets, chemical treatments all just create new issues. That being said ymmv and just when I have things figured out things go south lol.

After 3 years, that method has not controlled my nitrates well enough for me, plus water changes are expensive and time consuming. There are a lot of ways to have a successful tank, I am just trying something else.

davidwillis · Nov 8, 2023

jda said:
Lastly, for now, I like to have a sand bed to chew through waste products, like nitrate, so that I can feed a massive amount of food to get actually available sources of nitrogen to my corals in the form of ammonium from the fish. I can feed as much as I want and nitrate stays in a good place. Other phosphorous forms from the fish waste is better than po4 too, but this is harder to handle and requires to grow a LOT of chaeto, but orthophosphate as a waste product is another topic for another thread...

Thanks for your feedback, it is very useful!

jda · Nov 8, 2023

If you want to add onto this for po4, you could create a bucket where the water comes in from the top, drops through a sock (in a rack) and then goes out the bottom. Make it so that you can add/remove the sock in a few seconds. You can put the sock on, add some LC earlier in the system, have it mix with the water in the buckets to bind to the po4 and then everything drops through the sock. After a few minutes, you can take your low-micron sock of so that it does not get clogged up with other debris and use it for LC another day. LC works very well, but the socks are the worst part if you leave them on all of the time - taking them on/off just for the LC makes it easy and you don't have to do a deep clean as much.

davidwillis · Nov 8, 2023

jda said:
If you want to add onto this for po4, you could create a bucket where the water comes in from the top, drops through a sock (in a rack) and then goes out the bottom. Make it so that you can add/remove the sock in a few seconds. You can put the sock on, add some LC earlier in the system, have it mix with the water in the buckets to bind to the po4 and then everything drops through the sock. After a few minutes, you can take your low-micron sock of so that it does not get clogged up with other debris and use it for LC another day. LC works very well, but the socks are the worst part if you leave them on all of the time - taking them on/off just for the LC makes it easy and you don't have to do a deep clean as much.

I use a reactor that mixes the LC with tank water (I use my apex dos to dose very slowly 24 hours a day). The water then leaves the reactor and goes through a 50 micron, then a 5 micron filter. I only need to change these filters out about once a month. After the water is filtered, I send it to the buckets of sand. I like the idea of the bucket with the filter sock, but I don't have room under my tank, and my buckets are located above my mixing station, so it will be hard to get to. For now the reactor and micron filters are working good. with this system I can adjust the dosage of lc to get whatever level of po4 I want. I am currently keeping it close to 0.1 using a dosage of 17ml per day of diluted lc (I dilute more than the recommended dilution on phosban-l).

Court_Appointed_Hypeman · Nov 8, 2023

Just curious if my thinking on this is correct.

Lets say you have a remote sand bed that is a foot deep, the sand at the bottom of this will still be exposed to many of the chemicals in the water column correct?

Like, if bacteria that deep in the sand was consuming nitrogen, as that deep sand was depleting nitrogen, it would still be getting nitrogen from the water column correct?

The way I think about it is, it doesn't need to necessarily be mixing in order for the concentration of chemicals to be diluted into all connected waters right? Like the total concentration of a disolved compound would still be getting into barely moving waters. Am I right?

davidwillis · Nov 8, 2023

Court_Appointed_Hypeman said:
Just curious if my thinking on this is correct.

Lets say you have a remote sand bed that is a foot deep, the sand at the bottom of this will still be exposed to many of the chemicals in the water column correct?

Like, if bacteria that deep in the sand was consuming nitrogen, as that deep sand was depleting nitrogen, it would still be getting nitrogen from the water column correct?

The way I think about it is, it doesn't need to necessarily be mixing in order for the concentration of chemicals to be diluted into all connected waters right? Like the total concentration of a disolved compound would still be getting into barely moving waters. Am I right?

Yes the concentration of nitrogen (or anything) will attempt to equalize itself (osmosis). I am not sure if the flow rate really matters much, since the osmosis will be very slow anyway. My original water flow was very slow (about 8gph) but I replaced the pump, and now I am getting about 10X the flow. I did notice the drop this week was less, so I will let it go a few weeks, and then I may slow it down again to see if it make any difference.

jda · Nov 8, 2023

The depth at which the types of bacteria can grow will depend on availability (or flow to a lesser extent). The oxic zones up top will be deeper with more oxygen. The anoxic zones will be deeper with more nitrate. As the no3 level in the tank lowers, so does the no3 in buckets and the anoxic population will decrease to equilibrium. If you move more water through and 50% of the no3 gets turned into N gas, then this works the same as half as much water and nearly 100%. Nature is really good at this.

The DSB gurus always felt that microfauna helped to move the water between the levels - worms, pods, etc. This is probably right to some degree. However, water pressure can also do this. So can temperature and pH... the bottom of the bucket being even a few tenths of a degree cooler will move water by it's self. In the tank, the critters come with the territory. I have never seen remote DSBs void of life too - it just seems to find a way in there.

In nature, these anoxic zones along with plants and algae is what completes the nitrogen cycle. In some places, plants dominate and in others it is the anoxic bacteria in the substrate - in many places, there are both. The cycle is not just 14 days with Dr. Tims and a clownfish.

Mark Gray · Nov 9, 2023

Wow I don't have time right now to read all of this, but I will come back and do it. I have been in the hobby since the 70s. My current tank has gone through almost the same things. I got to go and help my wife right now but will come back and explain. Good luck