My sandbed

[Reef Bass]

I am coming to the conclusion that it may be time to replace my sandbed. It is 5 1/2 years old. I realize this is a subject of some controversy. My beliefs are that a sandbed not only looks good but can be of benefit to water quality at least until it becomes filled with noxious compounds and needs to be replaced.

The reason I think it is time is because I am noticing the onset of some disturbing "symptoms" or issues which I haven't had with the same tank and equipment in the last five years.

The biggest issue I'm noticing is that nuisance algae of various types are taking hold and increasing in quantity. I am experiencing a lot of a light green algae which tends to form a sheet on the sandbed and produce gas / bubbles. Not the usual dark green Valonia bubble algae which is like little dark green plastic bubbles but a light green velvety textured algae. It also likes to form on rocks around the tank. The good news is that when it gets to a sheet like state, I can vacuum up the entire sheet and peel it off the rock or sand easily.

I am also getting a dark colored deep reddish black brown algae forming on the rim of my purple rim green monti cap in the highest current area of the tank!

My lps and sps tanks share the same water system, and in my barebottom lps tank I am getting prodigous production of hair algae and other marine flora.

So that's three different algaes which are growing like mad with which I haven't had issues in the last five years with this same tank and equipment.

Ok, that's what I'm seeing. What I've been doing about it is micro target siphoning algae out, so there's an active export process. But the Super Hideous Invasive Trash keeps growing back, which to me means there is an ongoing nutrient source for these items.

Water quality - I strive to maintain my tanks with calcium 425, alk 9, mag 1300, nitrites / trates and phosphate at 0. My last test last week put my calcium at 400, alk 8.8, nitrates 5 and phosphates 0.

I find it odd that I have algae issues with nitrates 5 and phosphates 0, as I've had nitrates of more than 10 before without significant algae problems. My understanding of "old sandbed syndrome" is that this is one of the signs (lots of algae with low standard nutrient tests results).

The question of "well, what have you changed recently" is relevant. The biggest recent changes have been the addition of my lps tank to the water system, my having adopted a reasonably consistent lps feeding strategy and my having automated my dosing.

I don't think the addition of my lps tank (60g 48x24x12) to my exisiting 100g water system is the cause. If anything, that should help, because I have 50%+ more water with the same stock level.

Clearly overfeeding my lps could be a cause of unwanted algae production. However, if that were the case, I would expect the usual nitrate and phosphate water tests to show elevated levels, which they don't. Plus I'm target feeding only twice a week and only what the polyps actually consume. There's not a pile of uneaten food left over. And most of the time I come back about 12 hours later and siphon out any acan poop - digested remains that have been expelled after the polyp has consumed what it wants. So I doubt this is the cause of my algae woes. And of course my fabulous EuroReef skimmer is skimming 24/7/365.

If my feeding were overwhelming my skimmer, I would expect to see a significant increase in skimmate production (haven't seen it) and also elevated NO3 and PO4 levels, which I don't.

Automating my dosing of ca, alk and mg has resulted in more stable and consistent parameters, which has made my corals very happy. I don't think this would necessarily cause an increase in nuisance algae production.

If you're still with me, thanks for reading so far!

That's why I think my sandbed needs to be replaced. Here's how I plan to do it. I am very concerned about a cycle and ammonia / nitrite spike. The last thing I want to do is kill my corals for sure by trying to replace the sandbed that is maybe causing me issues.

I am thinking about adding a shallow (1-2") sandbed to my lps tank. Being an lps tank there isn't enough flow to keep debris suspended in the water column until it can be removed in the sump, so the barebottom thing isn't working for me. I'm thinking that adding live sand and waiting a month before proceeding will give the lps tank sandbed time to build up enough bacteria to help moderate a potential cycle spike in the sps tank.

Then, in a long day, I plan to fill buckets with existing tank water and put my corals and rocks in them while I empty out the 100g sps tank, remove the old sand, add new live sand and replace rock and corals. That's going to be a ton of good smelling fun.

While I am confident about the mechanics of removing and replacing the sandbed, I am not sure about what will happen after it has been completed. Will there be a monster coral killing ammonia spike afterwards as the new sand cycles? Or will the spike not be too bad being in an established system and with the sand in my lps tank helping to keep elevated levels under control? Do you even think my accelerating issues with various algaes are due to old possibly nasty sandbed?

Thanks for reading all this. As you can tell I've given the issue some thought and would appreciate hearing from those who have grappled with similar issues. What do you think?

 

[northbay-reefer]

Reefbass, you are correct, the sand bed not only serve as a bacteria bed to help keep your tank clean, but it also act as a buffer to maintain your PH so it is a good thing to have. But an old sand bed will also create problems if you don't keep it cleaned. The problem with most reef tank is the sand bed ended up covered by rocks and is hard to clean so after 5-10 years the sand bed ended up doing more harm than good IMO. People just forgot about or ignore maintaining the sand bed altogether. The other factor is your corals will grow so large that it will be very hard to maintain the sand bed. Some people have gone as far as having a remote sand bed for the added benefit and then keep their main tank bare bottom.

The way to replace the sand bed is to do it gradually by vacuuming and replacing a little bit each time, some do a 1/3 each time until it is replaced and then repeat the process after several years.

I am in the process of redoing my tank and part of the sand bed will be replaced, I will take all the rocks out, vacuum it aggressively and some of the sand will be lost through that process, and then I'll add more sand since my sand bed is only 1-2" deep. After that I will installed a new rock structure that is much more open to allow better maintenance of the sand bed. This is my new live test I think it will help with the longevity of my new set up. So 5 years from now I will let you know if it works or not .... LOL

 

[carne.espada]

Far be it for me to give advice on coral husbandry but being a formally trained biologist, I like to think some of my thought are fact based....
I agree that swapping out sand over time is a better idea. I think that using a shop vac to suck directly from the bed itself should give you a quick and complete way to remove sand. You will of course need to sift through the effluent to get any critters out so you can return them to the tank. I would probably make a custom suction hose that would incrcease suction and decrease volume for more control. Maybe like a 1/2 inch PVC nozzle/suction pipe? If you try to use siphon effect only, I don't think that you can get a good enough flow/uplift. My sand bed is the original from 7 1/2 years that the tank has been up. I don't see much change but I do think the buffer capacity is diminished. My pH doesn't stay as high as I would like and I attribute that to the old sand bed. What my old sand bed does have is an array of stars, snails, polychaetes and assorted other worms and creatures that I am sure benefit the overall ecosystem. I think that the big thing is goal. If you want a natural looking aquarium then I think that my tank is a pretty good execution, albeit primarily softees. If you are in the frag biz then you do what you and Jason have done, which I think is a great compromise. A tanks without fish is not very aesthetic, IMO.
The thought of the sand switch out you described makes my back hurt, by the way!
Good luck!

 

[Reef Bass]

Tom and Rob, thanks for your suggestion to replace the sandbed in phases. When I do replace it, I will take that approach. Rob I like the shop vac sand extraction idea.

I stopped by Caesars yesterday for some salt mix and spoke to James about my current issue (too damn much algae). His feeling was the substantial recent addition of new water volume when I added my lps tank to my water system was the culprit. His opinion seemed corroborated when we looked up the algae with which I am having the most trouble (the light green mat and bubble forming one) in one of his books and it is described as one which tends to be an issue in new systems with clean / fresh (recently made, not no salt) water.

As a side note, the bubbles being produced by that algae are full of oxygen, not hydrogen sulfide, ph lowering carbon dioxide or bazillions of algae spores. Yay!

Thinking back I did a 30% water change on my 100g right before adding the lps tank into the system with its 60 gallons of new water. So right there 90 of my 150-160 gallons were new / freshly made.

Fortunately for me, the one big nasty symptom of sandbed crash I am not seeing (yet anyway and hopefully never!) is RTN / STN of corals.

All the pieces of the puzzle are fitting together and it seems my algae issues are new water, not old nasty sandbed, based. At James' suggestion I am going to decrease the photoperiod of my actinics to match that of my MHs (no more hour before and after, at least until things improve). I will also be continuing to target siphon export algae (oh joy) and to be conservative with my lps feeding. I am going to put a regular / "dead" aragonite shallow sandbed in my lps tank for aesthetic and buffering purposes and will be leaving my 100g's sandbed alone (for now).

Reducing the available light and nutrients should throttle back the offending algaes until my enlarged water system stabilizes in the next month or two. I do see my 100g's sandbed as a potential issue down the road but for now it's off the hook.

 

[crispyreef]

When I last replaced my sand I used a hose and sucked up one half while doing a water change, then the other side the following week. I do see better results with a sand bed ime. When I moved my tank recently to the garage, I let the sand sit in the bucket too long and I didn't feel like cleaning it so I dumped it. Now my tank is semi BB and I don't feel like the water is as stable with out it. I plan on adding a little for the buffering and I think it looks good too. Good luck

 

[FreshReefer]

I don't know about replacing a sand bed but I do know I had similar issues with similar algae to what you are describing. My first RO system didn't have DI so I was constantly adding phosphates. I bought a hach test kit and later discovered that the phosphates can be low enough to be very hard to measure or be zero if the algae can consume it very quickly.

The aftermath of the phosphates I could never measure until I tested the water before I added it to the tank with the TDS meter. It was measuring below 10 but still caused green hair algae. Then I vacuumed it and wound up with a cyano outbreak.

Here is the interesting part... When I added the phosban reactor and got a DI filter the cyano turned dark and almost black. It was easy to vacuum up after it changed colors just like you describe. Also the reactor caused the hair algae to turn brown and as time went on with no phosphates it got shorter and eventually was gone.

All I am saying is check everything you add to your tank before you mess with the ecosystem. If there is a simple solution it may save you a lot of grief and hard work.

 

[Reef Bass]

Thanks for your input Owen. If I need my algaes to turn colors I'll send you a PM. Just kidding...

Your advice to check everything added before messing with the tank itself is good. My water filter has two chloramine killing carbon canisters and two DI canisters and a TDS meter. The water going in to my tank has 0 tds.

I installed a shallow "dead" aragonite in my lps tank yesterday and boy does it look a whole lot better. No immediate change on algae (obviously) but I wasn't looking at this as an algae solution. Sure makes the tank look better! Barebottom wasn't working for me in that tank.

There is good news on the algae front. It is definitely growing slower. I cut 2 hours off my actinics (the hour before and after MHs) and the impact on the algaes has been noticable. I also think my corals are a touch pale compared to say last week but they're still glowing.