NT LABS Hardness Test - 80 Tests

What is KH

KH, also known as 'total alkalinity' or 'carbonate hardness', is a measure of the buffering capacity of the water in your aquarium. The buffering capacity refers to how well it can resist changes in pH.

What is GH

General Hardness is a measure of the total amount of minerals dissolved in the water. Water hardness lies on a spectrum between 'soft water' or 'hard water' depending on the amount of dissolved minerals: the more minerals present, the greater the hardness. Hard water is responsible for the build-up of limescale.

KH in detail

What is the correct KH level

This test kit measures KH in dKH (where one dKH = 17.8 ppm as CaCO3). It is essential to maintain a minimum KH level of at least 4 dKH at all times. A KH of between 6 and 8 dKH is more desirable.

What do I do if the KH level is wrong

Check the KH level of your tap water. If the level is above 6 dKH, then regular water changes should keep the KH value in the aquarium topped up at a reasonable level. If the KH value of your tap water is below 6 dKH, you will need to add a KH buffer such as KH Up – pH Stabiliser to your aquarium/pond.

How to use

• Ensure the test tube is clean.
• Take a 5 ml sample of water into the test tube.
• Take the KH reagent and add one drop, mix and the water sample should turn pale blue.
• Keep adding drops, one by one (remember to count the drops), mixing between drops, until the blue colour turns to yellow. The number of drops, including the first drop, needed to bring about the colour change is equal to the KH value in dKH. Should the first drop of reagent turn the sample yellow then the KH value is below 1 dKH – this is extremely dangerous for fish.

GH in detail

What is the correct GH level

This test kit measures GH in dGH (where one degree = 17.8 ppm as CaCO3). The correct GH depends on the type of fish being kept. For soft water species, aim for a GH of around 3 to 6 dGH, while for hard water species, 10 to 15 dGH is the correct range.

What do I do if the GH level is wrong

Test the GH of your tap water. The GH of tap water is determined by whether you live in a hard or soft water area. If the water is too hard for the fish being kept, alternative waters can be used, such as reverse osmosis water, to lower the GH. To increase the GH for aquarium fish, calcium carbonate rocks (like ocean rock) can be used to provide a continual source of GH minerals.

How to use

• Ensure the test tube is clean.
• Take a 5 ml sample of water into the test tube.
• Take the GH A reagent and add two drops.
• Mix and the water sample should turn dark pink. Adding one drop of reagent GH B at a time, mixing between drops, count the number of drops required for the solution to change from pink to blue.
• The number of drops needed to bring about the colour change is equal to the GH value in dGH. Should the first drop of GH B reagent turn the sample blue then the GH value is below 1 dGH and indicates very soft water.

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Next Day Shipping cut off is at Noon/12:00pm

Orders after that time will be processed the next working day

Please Note: Certain ponds, aquariums, all pond plants, and all livestock are excluded from free delivery.

The blue highlighted area on the map below is where we deliver on our own vehicle. Unfortunately, if you are not in one of these postcode zones we are unable to deliver certain items such as plants, small glass items and selective other products.

We offer a few different delivery options depending on the size and value of your order.

Certain orders over £50 qualify for free mainland UK (excludes Northern Ireland, Pond Plants, and livestock) delivery which will arrive within 3-5 working days of the order being processed.

Orders Below £50 in Mainland UK will be charged a standard delivery fee of £5.99.

Pond Plant and Tropical/Marine/Pond Livestock will be charged a delivery fee of £19.99.

Additional Shipping Charges

For any orders that do not include Aquariums, the below is charged:

Next Working Day Parcel Delivery to Mainland UK - £7.99 OR £2.99 if the order is over £50 (excludes Northern Ireland)

Standard Parcel Delivery to Northern Ireland £8.99

Standard Parcel Delivery to Scottish Highlands & Islands £9.99

Standard Parcel Delivery to Jersey & Guernsey £12.99

For all Aquarium, Medium - Extra Large Terrarium/Vivarium/Paludarium deliveries (Excluding biOrbs & Smaller Aquariums), the below is charged:

You must be present for delivery and please check your item before signing for delivery.

A payment link will be sent to you if redelivery is required.

Next Working Day Pallet Delivery - £20

2 Hour Booking Slot Pallet Delivery - £20

Pallet Delivery to Northern Ireland - £45

Saturday and OptiClear 90 & 120 Delivery - £60

Pallet Delivery to Isle of Wight (PO30 and Above) and Scottish Highlands (AB, PH, IV1-36, IV, KW1-14, KY, PA21-41) - £45

Pallet Delivery to the Scottish Isles (KA27-28, PA60-90, ZE, JE, GY, IM, IV40-56, KW15-17, PH42-44, PA20, PA42-49) - £120

Pallet Delivery to Outer Hebrides (HS) - £140

Pond's over 1000 litres will be a curb side pallet delivery.

Aquariums over 125 litre will be a curb side pallet delivery.

The couriers we use are Royal Mail, DX, APC, and UPN.

Standard Delivery

Northern Ireland Standard Delivery

Next Day Delivery

Cut off is Noon/12:00pm

Saturday Delivery

Cut off is Noon/12:00pm

Livestock Delivery

Cut off is Noon/12:00pm

Plant Delivery

Cut off is Noon/12:00pm

Standard Curb Side Pallet Delivery

Cut off is Noon/12:00pm

Next Day Curb Side Pallet Delivery

Cut off is Noon/12:00pm

Saturday Curb Side Pallet Delivery

Cut off is Noon/12:00pm

Northern Ireland Curb Side Pallet Delivery