What is the correct pH for a lobster tank?

The ideal pH for a Lobster Pod or Crab Pod is between 8.0 and 8.2 which is similar to natural seawater. Maintaining the correct pH is important for the health of lobsters, crabs and langoustines and helps the biological filter work efficiently.

In a closed recirculating system the pH can gradually fall over time. Regular testing allows you to identify changes and correct them before they affect your shellfish.

Why does the pH fall in a shellfish holding system?

The biological filter contains beneficial bacteria which break down waste produced by the shellfish. These bacteria convert ammonia into nitrite and then nitrate through a process called nitrification.

This process also produces acid which gradually lowers the pH of the water. Without regular monitoring and maintenance the water can become increasingly acidic.

As the pH falls the biological filter can also become less efficient at processing waste.

What happens if the pH is too low for lobsters and crabs?

Lobsters and crabs rely on the correct pH to regulate their internal chemistry and eliminate carbon dioxide from their bodies.

If the pH drops below 7.6 it can cause significant stress and affect their ability to regulate their blood chemistry. This can weaken the shellfish and increase the risk of mortality particularly during handling and transport.

Maintaining the correct pH is therefore important for both the health of your shellfish and the performance of your holding system.

How often should you test the pH in a lobster tank?

We recommend testing the pH at least once a week using multi-parameter water testing strips. More frequent testing may be useful when the system is heavily stocked or if you have previously experienced problems with falling pH.

All new Todd Fish Tech Lobster Pods and Crab Pods are supplied with water testing strips to help customers monitor their water quality.

How do you raise the pH in a lobster tank?

If the pH falls below 8.0 we recommend adding bicarbonate of soda (sodium bicarbonate) to help restore the correct balance.

Bicarbonate of soda helps neutralise the acidity produced by the biological filter and increases the water’s buffering capacity. This helps stabilise the pH and prevents it from falling too quickly.

For a 300kg Lobster Pod we normally recommend adding around one mugful of bicarbonate directly into the filter. Allow it to dissolve and circulate through the system before testing the pH again.

Use pure sodium bicarbonate rather than baking powder or products containing additional ingredients. Bicarbonate of soda can be purchased from Todd Fish Tech or from catering suppliers.

Why is regular pH monitoring important?

A falling pH can affect both your shellfish and the biological filtration system. By checking your water regularly you can identify changes early and make small adjustments before they become more serious problems.

We recommend including pH testing as part of your weekly water testing routine alongside ammonia, nitrite, nitrate and salinity.

If you need advice on your water test results or would like to order replacement water testing strips or bicarbonate of soda please contact us at hello@toddfishtech.com.

Last updated October 2026