Category Archives: Saltwater, Rock, & Sand

Live Rock – What Type is Best for Your Aquarium?

Live rock is the foundation of a saltwater aquarium. It plays a vital role in keeping your water clean and your aquarium healthy. It provides protection and shelter for your fish and critters. And it gives coral, sponges, and many other things a surface to grow on.

live rock with coraline
Live rock with coraline algae starting to grow on it.

There are several types of live rock to choose from. Let’s take a look at the advantages and disadvantages of some of the more popular options.

Pukani live rock:


  • Very light weight and very porous. Pukani rock provides a lot of surface area for both aerobic and anaerobic bacteria. This means it is very good at helping to remove ammonia, nitrites, and nitrates from the tank.


  • Most dry rocks that came from the ocean have high phosphates. However, many aquarists report Pukinai dry rock has more phosphate than any other type of live rock. High phospates can feed severe outbreaks of nuisance algae.

Tonga live rock:


  • Comes in several unique shapes including branches and shelves.
  • Fairly light weight and porous.


  • Like any dry rock that originally came from the ocean, it can have high levels of phosphate which may cause algae blooms as it leaches out of the rock into your tank water over the first 6-12 months of use.

Man-made live rock:


  • Eco-friendly. You know for certain it is not being harvested from living reefs.
  • Low to no phosphates.
  • Comes in different shapes such as branches and shelves.


  • Less porous than natural pukani or tonga rock.
  • Can be much pricier than other types of rock.

Florida Reef Rock:

Florida reef live rock is limestone rock that is quarried inland from deposits made up of what used to be ancient ocean reefs.


  • Eco-friendly. You know for certain it is not being harvested from living reefs.
  • Florida reef rock from respected sources such as and Marco Rocks are reported to have lower phosphates than most any other type of live rock.
  • Least expensive type of rock.


  • More dense, heavier, and often less porous than Pukani or Tonga rock. So you need to buy a bit more to get the same amount of surface area and biological filtration the other rocks provide.
  • This means more cost, and more weight in your aquarium.
  • If it also lacks very fine pores there will be nowhere for anaerobic bacteria to grow. So, while it may help process ammonia and nitrate, it will not be very effective at reducing nitrates … so some other means of nitrate removal will be needed.

Each type of live rock can be purchased from numerous sources whether it be online or at your local fish store.

And they can be purchased in different ‘states’.

By this I mean you can get pieces that are literally dry chunks of rock (old coral skeletons to be exact) that will need to be cycled and cured.

You can get pieces that have already been cured, cycled, and are shipped or bought wet. This means they are ready to use and have little or no other life on them other than the bacteria needed to consume the harmful ammonia, nitrites, and nitrates produced as waste by the fish and critters in your aquarium.

Or you can get pieces that are aqua-cultured and teaming with life. This means they not only have the need bacteria to act as a biological filter for your aquarium. They will also be covered in anything from barnacles and sponges to coral and crabs.

Each of these ‘states’ of dry rock has advantages and disadvantages as well, but that’s a topic for another article.

Tips for Calibrating Your Aquarium Refractometer

Few things can get your new aquarium off to a bad start quicker than a refractometer that isn’t properly calibrated. After all, saltwater is the first thing that goes into your new tank – get it wrong and you’re doomed to problems right from the start.

I almost learned that the hard way…

A used refractometer was posted for sale on my local Marine Aquarist Society forum, so I grabbed it.  It was in fantastic shape and I figured I could use the money I saved for some other equipment. The person selling it even tossed in a bottle of refractometer calibration solution.

The instructions that came with it called for using distilled water and calibrating it to zero. However, many aquarists believe it is better to use calibration solution that has the same salinity as natural saltwater (35 ppt, or 1.0265 specific gravity at 77° F / 25° C) since that is the specific solution/liquid they’ll always be using it to test.

To get ready for my first batch of saltwater, I let both the refractometer and the bottle of calibration solution sit in a room that was as close to 77° as possible for a few hours. Then I placed a few drops of solution on the refractometer and calibrated it to 35 ppt.

Then I mixed my saltwater.  It needed a little more salt (I’m using E.S.V.’s 4-part saltwater mix) than the instructions called for in order to reach 35 ppt. Other than that it was smooth sailing – the refractometer worked great. However, it turns out the calibration solution did not…

The day after mixing my saltwater and putting it in my new aquarium, the water turned hazy. At first I thought it was a little bacteria bloom – which is quite common in new tanks. But the next morning I noticed the water had cleared and left a white dust on the bottom of the tank. Something had precipitated out of the water – most likely calcium, possibly salt.

My immediate thought:  something isn’t right with the refractometer. So, I re-calibrated it – this time following the refractometer instructions and using distilled water (actually I used RODI water.)

Sure enough, the original calibration had set the meter way too low. Then I realized my mistake – I never asked the previous owner how old the bottle of calibration fluid was or how it was stored, and there is no expiration date stamped on the bottle. There was a VERY good chance some of the base liquid evaporated off, or the solution has surpassed its shelf life.

Thanks to a very handy online article Randy Holmes-Farley wrote on homemade salinity calibration solution in Reefkeeping Magazine, confirming my suspicion was pretty quick and easy – all it took was a quick trip to the grocery store for a 79 cent tub of table salt (no iodine added).

Per Mr. Holmes-Farley all you need to do is dissolve 36.5 grams of table salt in 963.5 grams (e.g. mL) of distilled water (again, I used RODI water). And this is a scale-able ratio. So, using a kitchen scale to measure, I just mixed 18g of salt in 481.75 g of RODI water. (The article also gives directions for using measuring cups if you don’t have a kitchen scale.)

I used my fresh, homemade solution to calibrate the refractomer. And then took a reading of RODI water on the refractometer – which measured exactly zero, confirming the refractometer was now properly calibrated.

With the properly calibrated meter in hand, I checked the water in my tank next.

Sure enough, the salinity was way too high.

Fortunately there was nothing in my tank yet but the saltwater. So I simply replaced a half-gallon at a time with some pure RODI water until it came down to 35 ppt (or 1.0256 specific gravity).

If this had happened when I had livestock in the tank, the results could have been disastrous.

So, here are three quick tips for calibrating your refractometer:

  1. If you use a manufactured calibration solution – whether it’s store bought or second-hand, make sure it’s relatively new and was well stored
  2. Better yet, make your own solution – it very easy, you KNOW it’s fresh each time you use it, and it costs less than $1 and 5 minutes to make
  3. Make sure your refractometer – not the calibration solution – is as close the calibration temperature stated in instructions that came with it as you can. (Don’t worry about the calibration solution temperature:  you’re only putting 2-3 drops of solution on the refractometer prism – within 30-45 seconds it will be the same temperature as the refractometer.).



Hazy Water in My New Tank – Help?!

The water is hazy in your new saltwater aquarium – and you haven’t even put anything in it yet…  Help, what the heck is going on?

If this happens to you (like it did to me) don’t freak out – turns out it’s actually fairly common.

There are several reason your fresh, very first batch of saltwater may turn hazy – even if you haven’t put anything into the tank yet.

3 Common Reasons for Hazy Water in a New Aquarium:

1. Bacterial Bloom

If the water is hazy in your new saltwater tank, this is most likely the cause – and don’t worry it’s quite normal, and often unavoidable. It is essentially the start of your tank’s ‘cycle’.

If you’ve done even just a tiny bit of research before setting up your new tank, you most likely know your tank will have to go through a cycle in which natural bacteria enter and achieve a balance in your tank. The two primary types of bacteria involved in the cycle are heterotrophic bacteria and autotrophic bacteria.

The autotrophic bacteria are the most important of the two, They consume inorganic substances – such as the ammonia produced by decaying detritus and waste – and convert it into less harmful nitrites and nitrates. They are the biological filters of the saltwater aquarium and one of the primary reasons for having live rock in your tank. For that reason, many people assume the cycle starts when the live rock is added.

Here’s the kicker though: It takes very little organic matter in a new tank for the cycle to start – even the oils from you skin can be enough to trigger the heterotrophic bacteria and begin a bloom.

When it happens, the water is hazy, like a drop or two of milk was put in the tank.

It happens quick – just a few hours – and can be a little unsettling. Here’s what mine looked like:

tank water is hazy
Notice how the fish picture looks a bit milk and unclear because water is hazy…

I did a lot of fidgeting with my gyre pump after putting the water in my tank. So a fair bit of oil and other microscopic organics from my hands enter the water. But I was unaware that was all it took to trigger a bacteria cycle. As a result, I wasted several hours tinkering with my return pump and testing my saltwater mix (thinking it was one of the next two culprits) before I finally realized it was a simple, common bacterial bloom.

The best way to deal with this type of bacterial bloom – wait it out. It will clear up in a couple of days once the two bacterium reach a balance. Water changes may reduce the haziness a bit, but there is no way you’ll be able to keep with the growth/death cycle of the heterotrophic bacteria enough to keep the water clear.

My plan is simply to add my live rock in two more days as I had originally intended, let it go through its normal cycle, and all should be fine and crystal clear once it’s done. I’ll report back later to verify it’s success.

Another common culprit to look for if your water is hazy is…

2. Micro Bubbles

You water may look silvery and cloudy if there micro bubbles present.  Look close enough and you should even be able to see them.

If you are experiencing micro bubbles, some potential causes to look for are:

  • Excessive agitation in your sump and/or not enough space or time for the bubbles to escape the water before entering the return pump. Ensure you have enough baffles/bubble traps and slow enough flow in your sump to give the bubbles time to rise to water surface before reaching your pump.
  • Cavitation in your return pump – check to make sure your pump rotor is clean and functioning normally, and that your return pump is not grossly over-sized for the amount of water you need to move.
  • A small leak in your plumbing – in most cases a plumbing leak will mean water dripping out of your system. But, while very rare, it is possible in some parts of your return plumping for a leak to result in air being drawn in instead.

The next common cause of hazy water occurs when using kalkwasser or 2-part dosing for corals.

3. Calcium Precipitation

Calcium precipitation can also cause hazy, white water. When this occurs, rather than looking like a drop or two of milk was added to the water, your water will be much cloudier. It can even be so cloudy that it looks like a tank full of skim milk.

Typically this is the result of an overdose of kalkwasser or . The calcium carbonate will precipitate out of solution when pH levels get very high for an extended period of time, forming a very fine white dust. When using 2-part dosing it possible for other minerals to precipitate as well – such as magnesium hydroxide.

If precipitation occurs, the most important thing to do is test your pH. If it is still over 8.6 you should use vinegar, soda water, or another means of lowering it. Afterward, just wait it out until the precipitate dissolves back into the water and clears after a few days. Then, work to re-balance your calcium and alkalinity levels. The high pH and rapid swings in calcium and alkalinity will stress the corals but they may recover.



1 Week Update (12/24/2015):  Turns out the hazy water wasn’t caused by a bacteria bloom, it was caused by a bad batch of refractometer calibration solution. You can see the quick story of this near-disaster here.

Fortunately, I caught the mistake in time, the first batch of live rock from my Tampa Bay Saltwater ‘Package’ has been added to the tank, and the cycle is progressing very smoothly – only 0.04 ppm ammonia so far!

Tank with base rock


1 Month Update (2/6/2016):  Other than the high salinity mishap, the rest of the cycle was quick and painless. Ammonia topped out at 0.40 ppm then fell to zero within 7 days. The remainder of the live rock – plus other goodies including a rock flower anemone, sea mat, snails, sea cucumbers, two gorgonians, a peppermint shrimp, hermit crabs and some macro-algae – were added on December 30.

Since then, I’ve introduced several corals to my reef in a box. Nitrates, pH, and alkalinity continue to hold within my desired range: NO3 is at 10-20 ppm (remember, my goal is for the tank to be slightly ‘dirty’ or nutrient/nitrate rich), pH is 8.2, and dKH is 10.

In other words, so far, so good.

Aquarium with live rock.
So far, so good!