Har-Tru Maintenance Guide (subsurface irrigated - HydroCourt)

Subsurface Irrigated Court Maintenance Guide

Keep your subsurface irrigated Har-Tru Courts, including HydroCourts, Hydro Grids and CalCap, in peak playing condition. Here’s everything you need to know about taking care of your subsurface irrigated courts.

Daily Court Maintenance

•  Groom the surface using a court rake to smooth out and level any accumulation of material and clean the tapes using a line broom. It is important to agitate subsurface irrigated courts on a regular basis to inhibit the growth of algae and fungus.

As-Needed Court Maintenance


Subsurface irrigated Har-Tru courts have a tendency to become very firm over time due to the high moisture content of the courts. The following activities should be undertaken on a regular basis to improve playability:

•  • Use a court rake or similar maintenance product to agitate the playing area daily.
•  Use a tow scarifier around the perimeter of the court to break up "hardpan", particularly on the low side of the court.


A subsurface irrigated Har-Tru court will develop depressions or low areas over time in certain high play areas, like baselines and service boxes. These depressions/low areas will be evident because water will stand in these areas after a heavy rain. Running a string line over the court will also highlight low areas. These low areas will need to be patched.

To patch a low area, follow these steps:

  • Scarify the low area with a lute or other scarifying equipment to rough up the surface - this helps the new HydroBlend material to bind and adhere to the existing court.
  • Spread new HydroBlend material into the low area.
  • Level HydroBlend material with a straight-edge (ladder or flat side of a lute).
  • Hand water and roll the low area.
  • You may need to repeat the process if the low area is particularly deep.


Subsurface irrigated Har-Tru courts rarely need to be rolled, primarily because the high moisture content keeps them firm and compact. However, subsurface irrigated courts should be rolled under the following circumstances:

  • After a top-dressing
  • Lines should be rolled if they start to get high

Top Dressing

Subsurface irrigated Har-Tru courts lose much less material on an annual basis than sprinkler-irrigated Har-Tru courts. However, subsurface irrigated Har-Tru courts will lose material over time due to the effects of wind, rain, and play. Subsurface irrigated Har-Tru courts in most regions of the country will lose +/- 1 ton per year (25, 80 lb. bags). Subsurface irrigated Har-Tru courts in Florida will lose +/- 2 tons per year (50, 80 lb. bags), due to more rain and year round play. In order to properly maintain a subsurface irrigated Har-Tru court, they must be top dressed on an annual basis.

To top dress, follow these steps:

  • Turn off the watering system and allow the court to dry out for 2-3 days.
  • Scarify the entire court surface using a tow scarifier, Court Devil or lute.
  • Patch low areas (see above).
  • Apply court surfacing material using a spreader.
  • Level the material using a straight edge, usually a ladder.
  • Hand water and roll the court.

Top Dressing Tips

  • You can either top dress using a small amount of material (8 bags per court) multiple times per year or top dress using a large amount of material (50 bags per court) once per year.
  • If you are going to add more than 25, 80 lb. bags at one time, you may also need to remove and replace the line tapes, as more than 25, 80 lb. bags may bury the lines.

Coarse Blend Material

Subsurface irrigated Har-Tru courts generate a smaller quantity of large particles that provide the sliding material on the top of the court. In order to replicate the sliding surface and playability of sprinkler irrigated Har-Tru courts, Coarse Blend surfacing material was developed. Coarse Blend is available in 80 lb. bags and includes only larger granules of Har-Tru surfacing material. It can be spread in small quantities on top of subsurface irrigated courts to provide some "sliding" top surface.

Long-Term Court Maintenance and Upkeep

Har-Tru courts require 1" of Har-Tru surface material for optimum playability, court stability and moisture retention. For this reason, all new subsurface-irrigated HydroCourts are built with +/- 40 tons (1,000, 80 lb. bags) of HydroBlend surfacing material. Each new HydroCourt is also built with a 1" in 30' slope to ensure adequate rainwater drainage. This means that a new single court will slope 4" (if it is sloped from end-to-end) or 2" (if it is sloped side-to-side).

Rain, wind and play over time will cause HydroBlend material to wash off the court and to migrate (or "shift") from the high side of the court to the low side of the court. Over time, your HydroCourt will lose the ideal surface depth of 1" and the slope of the court will begin to "flatten out". These changes will cause the court to shift under rolling, shift under play and drain poorly, resulting in less than optimum (possibly even dangerous) playing conditions. Consequently, subsurface-irrigated HydroCourts should receive a "laser-tapered" resurfacing every 7-8 years.

In a laser-tapered resurfacing, laser guided grading equipment is used to remove excess material at the low end of the court and add new material at the high end of the court to restore the proper court slope. Fast-Dry Courts, Inc. was one of the first companies in the United States to utilize this revolutionary technique to restore HydroCourts courts to a like-new condition.