The numbers behind
clear water.
Benchmarks, patterns, and seasonal guidance for aquariums, pools, spas, and ponds. Drawn from public health guidance and decades of hobbyist consensus, framed by Ally.
Reference
benchmarks.
Starting guidance, not personalised prescriptions. Species, equipment, and local water chemistry will shift the targets.
CDC recommends a minimum of 1 ppm in pools; 3 ppm in spas.
CDC Healthy Swimming
Outside this range chlorine effectiveness drops sharply.
CDC Healthy Swimming
Above 100 ppm chlorine becomes much less effective; many health codes cap at 90.
Pool & Hot Tub Alliance
Higher than pools because of warmer temperature and bather density.
CDC Healthy Swimming
More stable than chlorine at spa temperatures.
Pool & Hot Tub Alliance
Any detectable ammonia indicates an incomplete nitrogen cycle or overload.
American Veterinary Medical Association reference
Most community fish tolerate up to 40 ppm; sensitive species prefer under 20.
Hobbyist consensus, multiple aquarium associations
Matches natural seawater salinity.
Marine Aquarium Societies of North America
Reef keepers typically aim for 8 to 9 dKH for stable coral growth.
Reef Central reference
Daily swings of 0.5 to 1.0 are normal due to plant photosynthesis.
USDA Pond Management Guide
When something
feels off.
Read the symptom, learn the likely cause, and take the right first step.
Cloudy pool water
Hazy or milky appearance, visibility reduced
Low free chlorine, high pH, or poor filtration runtime
Test free chlorine and pH; shock if combined chlorine is present
Green pool water
Visible green tint, slippery surfaces
Algae bloom from low sanitizer or high phosphate
Brush surfaces, run filter 24h, shock with calcium hypochlorite
Foam in spa
Persistent foam after jets run
High TDS or organic buildup from lotions and cosmetics
Drain and refill if TDS exceeds 1500 ppm above source water
Ammonia spike in aquarium
Fish gasping at surface, red gills, lethargy
New tank syndrome, overstocking, or filter media replacement
30 to 50 percent water change with conditioner that detoxifies ammonia
Algae on aquarium glass
Green or brown film on glass and decor
Excess light or excess nutrients (nitrate, phosphate)
Reduce photoperiod to 6 to 8 hours and check phosphate levels
Pond fish stressed in summer
Surface gasping, reduced feeding
Low dissolved oxygen due to heat and algae respiration
Add aeration, partial shade, and reduce feeding
A year of
quiet care.
Your water reacts to the calendar. Here is what tends to matter, by season and by surface.
Spring
Q1Open early, balance alkalinity before chlorine, expect higher CYA demand
Restart filtration gradually, watch for ammonia as bacteria recover
Resume normal feeding as fish metabolism rises with warming room temps
Summer
Q2Test 2 to 3 times per week, sanitizer demand spikes with UV and bather load
Add aeration, monitor temperature daily, watch for low oxygen in early morning
Watch evaporation, top off with conditioned water to keep parameters stable
Fall
Q3Maintain sanitizer until water drops below 60F, then prepare for closing
Reduce feeding as temperature drops below 60F, cover to keep leaves out
Adjust heater set points if room temperatures drop overnight
Winter
Q4Closed pools still need monthly checks for water level and cover integrity
Stop feeding below 50F, keep an opening in ice for gas exchange
Watch for power outages, keep battery backup for air pumps
Your water deserves
its own numbers.
Ally personalises ranges and recommendations based on your livestock, equipment, and location. The benchmarks above are a starting point, your situation deserves more.