Category Archives: My 24g Tank Build

A DIY Nitrate Reactor for Your Aquarium

This DIY nitrate reactor is simple and inexpensive to make – and is great for keeping the nitrates in your aquarium below 2 parts-per-million.

I always struggled with keeping the nitrates in my 24g aquarium any lower than 12 ppm.

Two weeks after making this nitrate reactor, my nitrates fell to 2ppm. And for the past month they have continued to hold steady at 1 to 2 ppm.

Stuff needed to make the nitrate reactor:

  • Seachem De*Nitrate (every 1 liter treats up to 100g of aquarium water)
  • an empty mayonnaise jar with plastic lid (I just bought a cheap $2 bottle of fake mayo at the local grocery store and dumped the contents in the trash) – or any other jar with plastic; just make sure it’s large enough to hold enough De*Nitrate to treat your tank
  • a 1′ piece 1/2″ diameter PVC pipe (Home Depot, Lowes, or most any other local hardware store)
  • a 1/2″ PVC barbed insert x female adapter (FIPT x insert) (you will most likely have to order this online)
  • a 1/2″ PVC spigot x male adapter (Home Depot, Lowes, or most any other local hardware store)
  • a tube of JB Waterweld (Home Depot, Lowes, or most any other local hardware store)

The tools you’ll need to make it:

  • either a hacksaw or coping saw
  • a drill
  • 1/8″ drill bit
  • 1/4″ drill bit
  • 7/8″ drill bit
  • small piece of sandpaper (any grit)

How to assemble it:

  1. Use the 7/8″ drill bit to drill a hole in the center of the mayo jar lid. Lay the lid upside down on a piece of scrap wood to drill it so that pressing down on it with the drill won’t crack the plastic lid.
  2. With the lid still upside down on the scrap wood, use the 1/8″ drill bit to drill several small holes around the outer portion of the top of the lid. (These holes are how water will exit the reactor.)
  3. Use the saw to cut length of PVC pipe equal to the inside height of the jar.
  4. Glue the spigot end of Spigot x Male adapter onto one end of the piece of PVC pipe you just cut.
  5. Trim the opposite end of the PVC pipe just enough so that it is held snugly in place when you stand it in the jar an screw the lid down over the top it:with lid on
  6. Remove the pipe from the jar and use the 1/8″ drill bit to drill several holes in the bottom end of it. (The incoming water will flow down the pipe and then exit the pipe into the bottom of the jar.)
  7. Use sandpaper to remove any burrs from the bottom of the pipe, then use sandpaper to lightly scuff the inside bottom of the jar.
  8. Place some JB Waterweld epoxy on the bottom end of the PVC pipe, then press the bottom of the pipe into the bottom of the jar. Make sure the epoxy has stuck to both the pipe and the jar enough to hold the pipe in place.
  9. Place the lid on the jar so that it hold the pipe centered in place while the epoxy cures overnight.
  10. After the epoxy has fully cured, remove the lid, cover the top of the pipe with your finger, and pour the appropriate amount of Seachem De*Nitrate into the jar.
  11. Replace the lid and screw down until it is just snug.
  12. Screw the Barbed Insert x Female Adapter onto the top of the pipe sticking out of the jar until it is just barely snug.
  13. You are now ready to place it in your sump and attach your water feed to it making certain the flow rate through it will be no more than 50gph.

In my case, I tee’d a 1/2″ line off my main return pump line. And I stuck a cheap 2 Little Fishes Ball Valve in it to control the flow just before it enters the reactor.

I also used the spare space in the jar to hold a bag of granular activitated carbon and another mesh bag with some Seachem Phosguard in it.  That way I can get flow through all three types of filter media without have to use any electric pumps. (The fewer pieces I have to plug into my power strip, the better.)

To replace the Phosguard and carbon, I simply unscrew the barbed fitting, then unscrew the lid.

The De*Nitrate pebbles never need replacing, It is a good idea to rinse them off with clean water every now and then though. That way detritus build up won’t block the microscopic pores the anaerobic bacteria live in, and they can continue consuming the nitrates from your tank water.

Since De*Nitrate requires a flow of 30 to 50 gph to pass through it for optimal performance, I adjusted the ball valve to provide a flow of about 35 gph through the reactor.

Here are some shots of my nitrate reactor setup:

empty nitrate reactor
Empty nitrate reactor


media in reactor
De*Nitrate on the bottom, a bag of carbon and a bag of PhosGuard on top of it.


nitrate reactor in sump
Water flows down to the reactor, down through its center pipe, up through the media, and out the little holes in the lid.


nitrate reactor valve
Water is feed from my return line, though the ball valve, down into the reactor jar.

Cyanobacteria … or Spirulina algae?

Cyanobacteria is a common occurrence in saltwater aquariums. Aquariums under a year old seem particularly prone to outbreaks.

Cyano is typically red. But it can also be brown, blue-green, or even green.

Regardless of the color, it grows in slimy strands that form  ‘mats’ on the rock and sand.  (To see some great pictures of a typical red cyano out break, check out this page over at Melev’s Reef.)

So, when these green, slimy ‘mats’ began showing up on my rock and then my sand bed a few weeks ago, my first thought was cyanobacteria.

It looked like green cyanobacteria
I thought green-colored cyanobacteria was beginning to cover my ball sponge and sand bed…

However, my online research soon revealed that cyanobacteria has a little-known relative that looks exactly the same to the naked eye: spirulina algae.

And it’s important to know which one you are up against because the methods for treating the two can be quite different.

How can you determine if it’s cyanobacteria or spirulina algae?

Simple, with a few drops of hydrogen peroxide.

Chances are you already have a bottle sitting in your medicine cabinet. If not, you can pick up a regular bottle of 3% hydrogen peroxide at most any grocery store or corner pharmacy.

Simply place a few clumps of the cyano into a container along with 2 cups of water from your aquarium.

Add 1 ml (20 drops) of hydrogen peroxide to it and then let it sit for several hours.

Peroxide is deadly to cyanobacteria. It easily breaks the cyano down and kills it. But peroxide has absolutely NO effect on spirulina algae.


If the water turns the same color as the cyano, it means you are indeed up against cyanobacteria.

If the water remains clear and the ‘cyano’ clumps show absolutely no signs of dissolving, then it is NOT cyanobacteria.

There are several methods you can use to get rid of cyano.

Many aquarists use the old-school method of keeping their tank lights off and the entire room dim for 3 days in order to starve it of light.

In some cases this isn’t enough to do the trick though and the cyano returns a few days after the lights are turned back on.

Others recommend dosing the aquarium with peroxide using a dosage of 1 ml of peroxide for every 10 gallons of water twice per day for 14 days straight.

Mild doses of peroxide have been proven to wipe out cyano while being safe on all other tank inhabitants.

And still others swear by the use of products like ChemiClean and Red Slime Stain Remover.

In fact, Chemiclean will eliminate both cyanobacteria and spirulina.

From what I’ve read, the key to success with products like these is to follow the direction to the tee. That means making sure you oxygenate the water as much as possible with powerheads and/or air stones. And doing the recommended water change as soon as the treatment is complete.

As for me, well, the water in my test stayed clear so it’s not cyano. That means it’s either spirulina or some other form of algae.

I’m going to give my tank a few more weeks to see if regular water changes will lower my nutrient levels enough to both starve it out and bring my good bacteria back into balance with the bad bacteria.

If so, the outbreak I’m experiencing may clear up on it’s own.

If it doesn’t, I’ll probably pay a visit and order some Chemiclean.

Aqua-Cultured Live Rock – Pros and Cons

Want to go from empty aquarium to ready-to-go reef in a box as fast as possible? Aqua-cultured live rock is a very fun, quick way to get there.

Some people are die-hard fans of aqua-cultured live rock and others wouldn’t use it if you paid them. As for me, you can now count me as one of the die-hard fans. Here’s why…

This was my new 24g rimless tank two weeks ago:

new 24g tank

This is it one-and-a-half weeks ago:

Tank with base layer of aqua-cultured live rock

And this is it today – fully cycled, already containing several newly added coral frags, and just a couple weeks away from being ready for fish (although I won’t be adding fish for 75 days – I explain why in a future post):

Cycled tank with all 40 lbs of aqua-cultured live rock.


The first thing you need to do with a new saltwater aquarium is cycle the live rock you put into it. This usually takes 2-4 weeks when using regular, cured live rock and involves a LOT of water changes and rock scrubbing. And months if you start out with dry rock and cure it from scratch yourself.

By using fresh, uncured, aqua-cultured live rock I was able to cycle my tank in just over two weeks without any water changes and absolutely no rock scrubbing. My ammonia never went above 0.4 ppm.

Using aqua-cultured live rock doesn’t always guarantee a cycle that is this quick and smooth – it is not unheard for ammonia to go above 1 ppm and require one or more water changes. More often than not though it is quicker and requires few water changes than typical cured live rock — and almost never requires scrubbing of the rock.

There are a couple of other advantages to using fresh, uncured, aqua-cultured live rock as well, along with some disadvantages.

The pros of using aqua-cultured live rock:

  • Tons of life on the rocks right from day 1: Since fresh, aqua-cultured live rock has been pulled straight from the ocean floor just few days (or even hours) before going in your tank, it is covered in all kinds, of barnacles, mollusks, sponges, crabs, coral and other life – including ALREADY being home to the beneficial bacteria that live on live rock and make it such a beneficial ‘biological filter’ for your aquarium – which is the primary point of having live rock in the first place
  • It’s eco-friendly: the people who ‘farm’ aqua-cultured rock within the U.S. (and several other nations) are required to use either millennium-old coral rock that has been quarried from dry land, man-made rock, or legally harvested dry coral rock that is then dropped into the ocean populates with the bacteria and other sea life before being collected. In this way, no natural existing reefs are disturbed or illegally harvested
  • It can save you a ton of time and effort:  as you’ve already seen, it almost always takes far less time and effort to go from a new tank to a semi-mature tank versus other types of rock

Of course, like most things in life, it does have trade-offs…

The cons of using aqua-cultured live rock:

  • Tons of life on the rocks right from day 1: Wait, isn’t that supposed to be a ‘pro’? Well, yes… and sometimes no. Most of the life than can come in on freshly aqua-cultured live rock is very desirable – but now and then a few hitchhikers can tag along that aren’t, such as: mantis shrimp, gorilla crabs, stone crabs, whelks, and a few others. It all depends if you’re willing to deal with plucking them out of your tank if any do stowaway on the rock.
  • Slightly less freedom to aqua-scape the rock exactly how you want it: because you are working with randomly sized and shaped chunks of rock that show up on your doorstep HAVE TO go straight into saltwater and are already covered with a ton of life, you don’t have the leisure of choosing, drilling, chiseling, or fitting together a rock feature that exactly matches an aqua-scape you may already have in mind. You’re limited to working with and piecing together the shapes you get.
  • Extra shipping costsreally nice fresh aqua-cultured live rock can be had for between $5-$7 per pound. This compares quite well to the $7-$9 local fish stores frequently charge for regular, cured live rock. However, since the aqua-cultured live rock is so live and fresh it must be shipped overnight in bags of seawater- and this can make for some very significant shipping costs. How much total cost difference there will be between the two will depend on how much your local fish stores charge for their live rock.

If you are interesting giving fresh, aqua-cultured live rock a try there are several places online where you can get it – two of the most popular on the saltwater aquarium forums are Tampa Bay Saltwater (which is where I got mine from – it was a 20g ‘Package‘) and KP Aquatics.

As for me, I’ll definitely be going with aqua-cultured live rock if I set up additional saltwater aquariums in the future.