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From our technical experts

Certikin Main Drain – For Concrete Pools


  • 6″ Main Drain with Anti Vortex Grille
  • For Concrete Pools
  • HD33


Main Drain For Concrete Pools

Featuring Certikin’s unique grille design and available for concrete or liner pools the HD33 drain is used to draw the base water for filtering and is also used as the principal method of emptying the pool. Both concrete and liner types come complete with self-tapping fixings screws for added safety. Manufactured in white ABS.


  • 6″ Main Drain with Anti Vortex Grille
  • Product Code HD33
  • High flow – low velocity grille supplied as standard – Provides up to 50% more free flow area than other models
  • Anti-vortex design – protective film prevents damage during installation

Main drain selection
When choosing sump (main drain) size always assume that total flow may be directed to the plant room via the sump(s) – sump size should be chosen accordingly. In normal conditions flow will be divided between surface draw-off and sump(s) in ratio: 70% Surface/30% sump for skimmer type pools or 50% Surface/50% sump for deck level pools.


HD33 – Main Drain
Current regulations state that every pool must have at least two main drains. Therefore, at least one main drain on every pool will need the bottom port sealed off – the Certikin main drain body has a knock-out blanking plate in the bottom port to save you time and money on site.

Main Drains
On commercial or shallow pool applications stainless steel main drain grilles must be used – main drains must be arranged so that there is no risk of bathers being drawn towards them or entrapped. Regulations state that on all installations a minimum of 2 x main drains must be installed 2 metres apart.

How to treat green water

Find out all you need to know about algae and green water, how to treat it and how to cure it.

Returns Policy

Your rights to return goods are protected under the EU Distance Selling Directive.

You are entitled to cancel your order and return the goods within 7 working days for a full refund not including the cost of delivery. Do this by contacting us by email or telephone and quoting the order number supplied to you. Your refund will be paid within 30 days. You are responsible for the cost and risk of loss or damage when returning the goods, so you should take out enough postal insurance to cover their value. This cancellation policy does not affect your rights when we are at fault - for example, if goods are faulty or incorrectly-described.

Exclusions: Bespoke items (made to measure items) are not included and cannot be returned. If a bespoke item is faulty then the product warranty /guarantee will take effect.

Any goods returned should be in saleable condition.

These terms apply to your order. We may change our terms and conditions at any time, so please do not assume that the same terms will apply in the future.

None of these terms affect your legal rights and these are not diminished in any way. If any term is held to be invalid under any applicable statute or rule of law, that term is automatically omitted from the terms to minimum extent necessary to comply with the law and without affecting the validity or enforceability of the remainder.