All Posts by hartley

How do I use a salinity refractometer to check the water salinity of my volcano shrimp (opae ula) tank ?

There are the digital or the analog version of the salinity refractometer. 

Analog refractometer has a wide salinity range from 0 to 100 ppt.

Digital refractometer can show the measurement in second. It can also convert salinity between:
a) Practical Salinity Units (PSU)
b) Parts per thousand (ppt)
c) Specific Gravity (S.G.) 

I use a Salinity Refractometer to read the salinity of the salt water


The salinity refractometer comes in a box and consists of a eye dropper and a refractometer.

An eye dropper pickup a water sample for measurement using a salinity refractometer


The front plate of the refractometer open up to show a blue prism.

The front plate of the refractometer open to show a prism


Take a water sample from your volcano shrimp (opae ula) tank.

Take a water sample from your volcano shrimp (opae ula) tank


Place 1 to 2 drops of water sample on the blue prism.

Put a drop of distilled water on the blue prism of the refractometer


Close the cover and stand below a light.

The refractometer need a light source to reflect the reading.

Look into the front eyepiece front of the salinity refractometer


Look into the eyepiece of the salinity refractometer. Make sure you are facing a light source.

When the viewing angle is incorrect, the light cannot reflect into the prism properly. You will see a white salinity chart.

But if the viewing angle is correct, you will see a blue and white salinity chart. 

Girl looking into a salinity refractometer


There are 2 salinity chart on a salinity refractometer.

The right chart shows the salinity reading in ppt (Parts per thousand). The left chart shows the specific gravity (S.G.) reading. 


The correct measurement is taken on the blue and white divider line.

This reading here shows a salinity of 1.015 S.G. or 20 ppt.

Salinity chart of a refractometer

How do I setup my miniature volcano shrimp (opae ula) tank part 4 of 4 ?

We are now ready to setup a new volcano shrimp (opae ula) tank.

This is a glass jar from ikea that can hold up to 1800ml of water.

I am using a glass jar from ikea that hold 1800ml of water


Add a little coral sand as a substrate. I like coral sand as it act as an alkaline pH buffer in the water.

Add some coral sand into the glass jar


I like to use lava rock in my tank. It provide a hiding space for the volcano shrimp (opae ula).

There are also trace amount of various elements in these rocks, which are beneficial to the growth of the volcano shrimp (opae ula).

I like lava rock as it provide a hiding space for the volcano shrimp (opae ula)


Remove the acclimation kit but keep the water in the jar.

We are going to use it in the new volcano shrimp tank.

Remove the acclimation kit


Since there are no shrimps in the new tank, you can gently pour the remaining distilled water into the tank.

Pour the distilled water gently into the new tank


The picture on the left is our acclimatize volcano shrimp (opae ula), it comes with old water from the local fish store (LFS).

The picture on the right is our new shrimp tank, with new salt water.

We are going to transferred the volcano shrimp to the new shrimp tank.

You can see that the tank is only half filled, we need more salt water


This is a plastic flour sieve or strainer.

I use it as a net to catch the volcano shrimp and transfer them to the new tank. 

I use a flour strainer to catch the volcano shrimp


The advantage of such net is that it will not collapse and trap the volcano shrimp (opae ula).

Do not bring the old water from this container into the new tank.

We leave behind all the old water to prevent any virus, bacteria or contaminants being transferred to the new shrimp tank. 

I use a flour sieve as a net to catch the volcano shrimp


To avoid stressing the volcano shrimp, transfer them quickly into the new tank.

Transfer the volcano shrimp quickly into the tank


Leave the net in the tank for a while to release the shrimp.

The volcano shrimp will swim out slowly into its new environment.

Release the volcano shrimp into the new tank


The new tank is only half filled. 

We will prepare some more salt water and top it up slowly.

After the volcano shrimp has been transferred, we need to top up more salt water


Let us mix up another litre of salt water.

Empty the remaining distilled water into the measuring jar.

Empty the remaining distilled water into the measuring jar


Add another 15 grams of aquarium sea salt into 1 litre of distilled water.

This make 15ppt (parts per thousand) of salinity.

Take another 15 gram of salt in one litre of distilled water


Stir and dissolve the aquarium sea salt.

Stir and dissolve the aquarium sea salt into the distilled water


This is another drip acclimation setup to adjust the volcano shrimp (opae ula) to the new salt water slowly.

Take as long as possible to acclimate the shrimp to reduce stress and mortality.

You can stop when the tank is 3/4 full.

You need some empty space at top of the tank for air exchange.

I setup another drip acclimation system to adjust the volcano shrimp to the new environment


Here is a picture of my dusty old tank.

It receives indirect sunlight daily and is full of algae.

My old 1.5L volcano shrimp (opae ula) tank


I drilled a small hole on the top cover to allow air exchange. 

Over the years, I found out that the gas exchange is very important.

It allow high success in breeding of my volcano shrimp (opae ula) and the survival of its larvae.

The jar is full of algae and the volcano shrimp population are thriving


This is a thriving colony of my 1.5L miniature volcano shrimp (opae ula) tank.

Top close up view of my volcano shrimp (opae ula)

How do I setup my miniature volcano shrimp (opae ula) tank part 3 of 4 ?

I use a red brick to elevate the measuring jar. You can also use other item too.

The objective is to allow the water to flow from a higher point to a lower point.

I use a red brick to elevate the measuring jar


This is my DIY aquarium acclimation kit for my volcano shrimp (opae ula).

It cost less than S$5.

I use a measuring jar, air tubing, adjustable air valve and a clothes peg to diy an aquarium acclimation kit


I use the clothes peg to clip and hold the air hose tubing during the drip acclimation process.

drip acclimation setup


I suck on the air hose tubing to draw up the water from the jar.

Give the air hose tubing a suck


When  water flow out from the air hose tubing, squeeze the tubing to reduce the flow and insert the adjustable air valve.

DIY drip acclimation kit


Once you have attached the adjustable air valve to the air hose tubing, tighten or loosen the red screw for flow rate adjustment.

 The flow rate is about 1 drop per second.

Attach the adjustable air valve to the air hose tubing


Drip acclimation the volcano shrimp (opae ula) will take between 1 hr to 3 hrs.

The longer the process, the less stress the shrimp will need to go through.

DIY drip acclimation process


Once the water in the container is about 5 times the original volume,  the volcano shrimp (opae ula) has been acclimatized.

You can proceed to setup and transfer the shrimp to the new tank.

It is a good practise not to use the water from the local fish store (LFS). The is to prevent any disease or bacteria contamination.

Drip acclimation my volcano shrimp (opae ula)

How do I setup my miniature volcano shrimp (opae ula) tank part 2 of 4 ?

Wash and clean the item with clean water. Do not use any disk washing detergent or soap. 

This is to prevent any leftover chemicals from killing the volcano shrimp (opae ula).

Pour the bag of volcano shrimp into a clear container. I prefer clear container as I can put a piece of colour paper underneath. This way I can easily differentiate the shrimps.

bag of volcano shrimp


Remove as much water from the container as possible. We are going to prepare and add in new water a little at a time. This process is called drip acclimation.

volcano shrimp (opae ula) in small container


Open a bottle of distilled water and pour it into the measuring jar. I do not recommend tap water or mineral water due to chemicals in the water.

a bottle of 1.5 Litres distilled water cost around S$2.


Pour 1 Litre or 1000ml of distilled water into the measuring jar. 

Pour 1 Litre of distilled water into a measuring jar

1 litre or 1000ml mark

Pour 1 Litre of distilled water into the measuring jar


Take a spoonful of aquarium sea salt . Any brand of aquarium sea salt is fine.

Here I am using Red Sea salt. 

Take a spoonful of aquarium sea salt


For those of you who do not own a salinity refractometer or hydrometer, you can use a weighing scale to measure the amount of aquarium sea salt.

Weigh a spoonful of aquarium sea salt on a weighing scale


Weigh 15 gram of sea salt exactly.

15 gram of aquarium sea salt


Pour the salt into the measuring jar.

Mix 1 Litre of distilled water with 15 gram of  sea salt.

It will  give you 15 ppt (parts per thousand) of salinity.

It is also equivalent to a (specific gravity ) S.G. of 1.0113.

Mix 1000ml of distilled water with 15 gram of sea salt


To get the correct salinity of the salt water solution, all the salt must be completely dissolved. 

You must dissolve all the aquarium sea salt in the jar


Stir thoroughly to dissolve the aquarium sea salt.

Stir completely to dissolve the aquarium sea salt

How do I setup my miniature volcano shrimp (opae ula) tank part 1 of 4 ?

List of item to prepare:

1) Jug with lid
2) Lava rock (small)
3) Coral sand
4) Stirrer
5) Net
6) Refractometer or hydrometer
7) Marine aquarium salt
8) Small container
9) Measuring Jug
10) Aquarium air hose
11) Adjustable air valve
12) Clothes peg
13) Brick
14) Weighing scale
15) Paper
16) Distilled water
17) Volcano Shrimp (opae ula)


I prefer glass over plastic as it is less likely to scratch. The glass clarity is better and it is also easier to clean. The main disadvantage is the heavy weight.

Here I am using a VARDAGEN Jar with lid, clear glass 1.8 litres from ikea.

Ikea VARDAGEN Jar with lid, clear glass 1.8 Litre


Choose a few pieces of lava rock small enough to fit in the jar.

Small pieces of lava rock to fit into the jar


Coral sand is bright.  It contains calcium that also buffer the alkalinity of the water.

It buffered the alkalinity of the water


You will need a stirrer to dissolve the aquarium salt in distilled water.

Use a spoon or stirrer to mix the salt into the distilled water


You need a net or sieve to catch the volcano shrimp or opae ula.

I use a plastic fine mesh flour sieve or strainer to catch my shrimp


You need a salinity refractometer or hydrometer to measure the salinity of the salt water solution.

Salinity Refractometer for Seawater and Marine Fishkeeping


It is a must to use aquarium sea salt to mix the salt solution for your shrimp tank.

Use only Aquarium Sea Salt. Do not use other types of common cooking salt !


Use a small container to temporary house the volcano shrimp (opae ula). We will use this container to adjust or acclimate the shrimp.

Plastic container use to acclimate the volcano shrimp


A measuring jar is used to measure the volume of water for the tank.

Measuring jar to measure the volume of water


I use an aquarium air hose and an adjustable air valve to acclimate the volcano shrimp (opae ula).

Use an air tubing and an adjustable air valve to acclimate the volcano shrimp

Use an air tubing and an adjustable air valve to acclimate the volcano shrimp


You need a clothes peg to help you hold on to the air tubing.

Plastic clothes peg to hold the air tubing


The brick is used to elevate the jar of salt water.

The brick is used to elevate the jar of salt water


If you do not wish to get a salinity refractometer or hydrometer, you can use a weighting scale to measure the weight of the sea salt.

I use a weighing scale to measure the weight of the sea salt


Use a piece of paper to hold the sea salt

I use a piece of paper to hold the sea salt for measurement


You can make your own distilled water or buy bottled distilled water for your volcano shrimp tank.

You can buy bottled distilled water


The tank size will determine the number of volcano shrimp (opae ula) you can keep. Usually for small tank, I will keep a population between 8 to 20 shrimps. This allow a higher ratio of having male and female shrimp.

A population of between 8 to 20 volcano shrimp (opae ula) in a bag

How can I adjust or acclimatize my volcano shrimp (opae ula) to the new tank or new environment ?

Water chemistry, temperature and pH are different in all the tanks. I usually adjust or acclimate my volcano shrimp (opae ula) to avoid any losses or death.

To acclimate the volcano shrimp, I put the volcano shrimp into a small containers with a small amount of water. Then I add a very small amount of water from the new tank every 30 minutes.

Repeat again.

Once the containers is full, pour away half the water. 

Repeat and add a very small amount of water from the new tank again, every 30 minutes. 

Alternatively, you can follow my diy setup of an automatic drip acclimation system. But you need to check the tank as often as possible to avoid overflow !

Or you prefer to just buy an aquarium fish acclimation kit online.

I acclimatize the volcano shrimp (opae ula) with a plastic jug, air hose and an adjustable air valve

How do I catch my volcano shrimp (opae ula), what fish net should I use part 2 of 2 ?

Over the years of keeping volcano shrimp (opae ula), I had many losses and death.

Some silly mistakes included trapping a volcano shrimp (opae ula) into a corner, accidentally squeezing it to death.   

Other time, I overlooked a volcano shrimp (opae ula) still trapped in the fold of the net. By the time I found out, it was dead.

Nowadays, I use a plastic sieve also known as a flour sieve or fine mesh strainer to catch my volcano shrimp (opae ula). It is much safer this way !

I use a plastic fine mesh flour sieve or strainer to catch my shrimp

How to prepare salt water solution for my volcano shrimp (opae ula) tank ?

Whenever I prepare a new batch of salt water for my volcano shrimp (opae ula) tank, I need a way to measure the salinity.

Too much salt and it will kill the volcano shrimp. Too little salt and the volcano shrimp (opae ula) will not breed. 

So the exact amount is required. 

I use an inexpensive analogue specific gravity (S.G.) meter, also called a salinity meter or hydrometer. 

I measure the amount of salt in my volcano shrimp (Opae ula) tank using Specific Gravity Meter or Salinity meter


There is also a digital salt meter called Koi Medic salt meter which measures the salinity in percentage or parts per thousand (ppt).

It is a bit more expensive but you can read the result instantly and not get your hand wet. 

The drawback is the limited salinity range, between 0% to 2% for this model.

The digital salinity meter called Koi Medic Salt Meter


This is a simple analogue salinity meter.

I like it because I do not need to deal with flat batteries and leaking batteries.

It has a wide salinity range from 0 to 100 ppt (parts per thousand) and is inexpensive.

I use a Salinity Refractometer to read the salinity of the salt water

What kind of natural decoration can I use in my volcano shrimp (Opae ula) tank 2 of 2 ?

I also like to use coral chips in my volcano shrimp tanks as a decoration.

It contains calcium, magnesium, boron, nickel, sodium, sulphur, strontium, uranium and and other trace elements.

Coral chips are used in my shrimp tanks as a decoration and also buffer my water parameters


These elements buffer the water and helps in the growth of the volcano shrimp (opae ula).

As the shrimp mature, it shed away its shell or exoskeleton, this shedding process is called molting.

Coral chip and lava chip comparison. I used both in my tanks.