Skimmer API Reference

Calculate pool chemical dosing recommendations using Skimmer formulas.

The Skimmer endpoint automatically resolves the formula from your pool's sanitization type and applies wall-type target overrides — you only need to provide readings and pool size.

Endpoint

POST https://api.poolcloud.com/api/skimmer/
Content-Type: application/json

No authentication required.

Request Body

Field	Type	Required	Description
`readings`	object	Yes	Current pool water readings as `{reading_id: value}`. See reading IDs.
`pool`	object	Yes	Pool information. See pool object.
`formula_id`	string	No	Override the auto-resolved formula. See formula IDs. If omitted, resolved from `pool.water_type`.
`target_levels`	array	No	Override target ranges (highest priority). See target levels.
`substitutions`	object	No	Override default treatments. See substitutions.

Pool Object

Field	Type	Required	Description
`gallons`	number	Yes	Pool volume in gallons.
`water_type`	string	No	Sanitization method. Used to auto-resolve the formula. One of: `chlorine`, `salt_water`, `bromine`, `minerals`, `biguanide`, `copper`, `ozone`, `uv`. Defaults to `chlorine` if omitted.
`wall_type`	string	No	Pool surface material. One of: `vinyl`, `plaster`, `fiberglass`, `concrete`, `pebble`. Automatically adjusts calcium hardness target for porous surfaces.

Formula Auto-Resolution

If formula_id is omitted, it is resolved from pool.water_type:

`water_type`	Resolved Formula
`chlorine` (default)	`skimmer-chlorine_cal_hypo`
`salt_water`	`skimmer-salt`
`bromine`	`skimmer-bromine`
`minerals`	`skimmer-minerals`
`biguanide`	`skimmer-biguanide`
`ozone`, `uv`	`skimmer-chlorine_cal_hypo`
`copper`	`skimmer-minerals`

Target Range Priority

Target ranges are resolved in this order (highest priority wins):

Reading defaults — built into each reading (e.g. pH 7.2–7.6)
Formula-level overrides — per-formula adjustments (e.g. salt CYA 60–80)
Wall-type overrides — automatic for porous surfaces (plaster/concrete/pebble → CH 200–275)
User-provided target_levels — your request body overrides everything

Target Levels

An array of objects to override target ranges:

Field	Type	Description
`id`	string	The reading ID to override (e.g. `"fc"`, `"ph"`).
`min`	number	Minimum target value.
`max`	number	Maximum target value.

Substitutions

Override the default treatment for a reading direction:

{
  "fc": { "up": "dichlor" },
  "ph": { "down": "sodium_bisulfate" }
}

Field	Type	Description
`up`	string	Treatment ID to use when raising this reading.
`down`	string	Treatment ID to use when lowering this reading.

Response

{
  "actions": [
    {
      "readings": [
        { "id": "ph", "name": "pH", "short_name": "pH", "units": null }
      ],
      "type": "raise",
      "treatment": {
        "id": "ph_increaser",
        "name": "pH Increaser",
        "type": "dryChemical",
        "concentration": 100,
        "description": "Sprinkle (or \"broadcast\") pH increaser directly over the surface of the pool...",
        "waitMinutes": 20
      },
      "ounces": 11.2,
      "treatment_options": [
        { "id": "ph_increaser", "name": "pH Increaser", "type": "dryChemical", "..." : "..." },
        { "id": "soda_ash", "name": "Soda Ash", "type": "dryChemical", "..." : "..." }
      ]
    },
    {
      "readings": [],
      "type": "special",
      "treatment": { "id": "wait", "name": "Wait", "type": "wait" },
      "ounces": 20,
      "treatment_options": []
    }
  ]
}

Action Object

Field	Type	Description
`readings`	array	The readings this action addresses. Each has `id`, `name`, `short_name`, `units`.
`type`	string	One of `"raise"`, `"lower"`, `"special"`, `"warning"`.
`treatment`	object	The recommended treatment.
`ounces`	number	Amount in ounces. For warnings: delta from ideal. For waits: minutes.
`treatment_options`	array	Alternative treatments the user can choose from.

Treatment Object

Field	Type	Description
`id`	string	Treatment identifier.
`name`	string	Display name.
`type`	string	One of `"dryChemical"`, `"liquidChemical"`, `"task"`, `"wait"`, `"warning"`.
`concentration`	number	Percent active ingredient (0-100).
`description`	string	Instructions for applying the treatment.
`waitMinutes`	number	Minutes to wait after applying before the next treatment.
`taskName`	string	(Optional) Short name for task-type treatments.

Formula IDs

ID	Name	Description
`skimmer-chlorine_cal_hypo`	Skimmer Chlorine	Standard chlorine pools. pH: 7.2–7.6, TA: 80–120.
`skimmer-salt`	Skimmer Salt	Salt water pools. CYA: 60–80.
`skimmer-bromine`	Skimmer Bromine	Bromine pools.
`skimmer-minerals`	Skimmer Minerals	Mineral system pools. FC: 0.5–4.
`skimmer-biguanide`	Skimmer Biguanide	Biguanide pools. No chlorine/bromine.

Reading IDs

ID	Name	Units	Default Target	Notes
`fc`	Free Chlorine	ppm	1 – 3	Warning: +2 above max
`tc`	Total Chlorine	ppm	—	Offset by FC. Used to infer CC.
`cc`	Combined Chlorine	ppm	0 – 0.1	Inferred: TC − FC. Triggers shock.
`ph`	pH	—	7.2 – 7.6
`ta`	Total Alkalinity	ppm	80 – 120	Warning: +20 above, +10 below
`cya`	Stabilizer (CYA)	ppm	30 – 50	60–80 for salt pools. Warning: ±10
`ch`	Calcium Hardness	ppm	175 – 225	200–275 for plaster/concrete/pebble. Warning: ±25
`salt`	Salt Level	ppm	2700 – 3500	Salt pools only.
`bro`	Bromine	ppm	3 – 5	Bromine pools only.
`phosphate`	Phosphate	ppb	0 – 200
`iron`	Iron	ppm	0 – 0.2
`copper`	Copper	ppm	0 – 0.2
`tds`	TDS	ppm	500 – 1500
`borate`	Borate	ppm	70 – 90
`biguanide`	Biguanide	ppm	30 – 70	Biguanide pools only.
`biguanide_shock`	Biguanide Shock	ppm	100 – 300	Biguanide pools only.
`temp_f`	Water Temperature	°F	—	Monitoring only. No treatment.

Treatment IDs

Chemical Treatments

ID	Name	Type	Wait
`calc_hypo`	Chlorine Granules	dryChemical	15 min
`na_hclo`	Liquid Chlorine	liquidChemical	60 min
`chlorine_tablets`	Chlorine Tablets	task	60 min
`dichlor`	Dichlor	dryChemical	15 min
`bromine`	Bromine	dryChemical	20 min
`soda_ash`	Soda Ash	dryChemical	20 min
`ph_increaser`	pH Increaser	dryChemical	20 min
`m_acid`	Muriatic Acid	liquidChemical	20 min
`sodium_bisulfate`	pH Decreaser	dryChemical	20 min
`baking_soda`	Baking Soda	dryChemical	20 min
`alk_increaser`	Alkalinity Increaser	dryChemical	20 min
`cal_chlor`	Hardness Increaser	dryChemical	480 min
`cya`	Stabilizer	dryChemical	20 min
`salt`	Pool Salt	dryChemical	0 min
`shock`	Chlorine Shock	dryChemical	480 min
`iron_remover`	Metal Remover (Iron)	liquidChemical	60 min
`copper_remover`	Metal Remover (Copper)	liquidChemical	60 min
`borate_increaser`	Borate Increaser	dryChemical	20 min
`biguanide_sanitizer`	Biguanide Sanitizer	liquidChemical	20 min
`biguanide_oxidizer`	Biguanide Oxidizer	liquidChemical	20 min
`phosphate_rem`	Phosphate Remover	liquidChemical	60 min

Task / Special Treatments

ID	Name	Description
`swg_up`	Increase SWG Output	Turn up the salt chlorine generator dial.
`drain`	Dilute Pool	Partial drain and refill.
`drain_fc`	Dilute Pool (FC)	Stop adding chlorine or partial drain.
`drain_cya`	Dilute Pool (CYA)	Stop stabilized chlorine, partial drain.
`drain_ch`	Dilute Pool (CH)	Partial drain with hose filter.
`tds_drain`	Drain & Refill (TDS)	Partial drain to lower TDS.
`wait`	Wait	Auto-inserted between treatments. `ounces` = minutes.
`warning`	Warning	Reading slightly out of range. `ounces` = delta.

Examples

Minimal Request

Just readings and pool size. Formula defaults to chlorine:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": { "fc": 0, "ph": 7.0, "ta": 60 },
    "pool": { "gallons": 10000 }
  }'

Salt Water Pool

Auto-resolves to skimmer-salt formula with CYA target 60–80:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": {
      "salt": 2000,
      "fc": 2, "tc": 2,
      "ph": 7.4, "ta": 100,
      "cya": 40, "ch": 200
    },
    "pool": {
      "gallons": 15000,
      "water_type": "salt_water"
    }
  }'

Plaster Pool with Auto CH Override

CH target automatically raised to 200–275 for plaster:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": {
      "fc": 2, "tc": 2,
      "ph": 7.4, "ta": 100,
      "cya": 40, "ch": 180
    },
    "pool": {
      "gallons": 10000,
      "wall_type": "plaster"
    }
  }'

Biguanide Pool

No chlorine or bromine — uses biguanide sanitizer and oxidizer:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": {
      "biguanide": 20,
      "biguanide_shock": 50,
      "ph": 7.4, "ta": 100, "ch": 200
    },
    "pool": {
      "gallons": 12000,
      "water_type": "biguanide"
    }
  }'

With Custom Target Levels

User overrides take highest priority:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": { "fc": 2, "ph": 7.5, "ta": 100 },
    "pool": { "gallons": 20000 },
    "target_levels": [
      { "id": "fc", "min": 3, "max": 5 }
    ]
  }'

With Substitutions

Use dichlor instead of the default chlorine treatment:

curl -X POST https://api.poolcloud.com/api/skimmer/ \
  -H "Content-Type: application/json" \
  -d '{
    "readings": { "fc": 1, "ph": 7.4 },
    "pool": { "gallons": 15000 },
    "substitutions": {
      "fc": { "up": "dichlor" }
    }
  }'

Error Responses

400 — Bad Request

Invalid formula_id or calculation error:

{ "error": "Calculation failed: Unknown formula_id \"invalid\". Valid IDs: skimmer-chlorine_cal_hypo, skimmer-salt, skimmer-bromine, skimmer-minerals, skimmer-biguanide" }

422 — Validation Error

Missing required fields:

{ "error": "Validation error", "detail": "..." }

504 — Timeout

{ "error": "Calculation timed out" }

MCP Server (AI Integration)Formula Guide