Introduction
Quinta do Conde grew in a very particular way: generous plots, building carried out in phases over decades, and many pools built in stages — some by companies, some by the owner, some by a neighbour who knew about construction.
The result is a stock of pools with one dominant characteristic: almost none of them has any documentation. Nobody knows the exact volume, nobody knows the pump's flow rate, nobody knows where the pipework runs, and there is no technical sheet at all.
That is not a problem in itself. It becomes a problem the day there is a leak, or a dose that has no effect, or a pump to replace. This article is about establishing a baseline on a pool with no history — in Quinta do Conde, Fernão Ferro, Cabanas or any pool built without documented plans.
Why Missing Data Costs Money
Three concrete examples, all frequent.
Dosing. Every chemical dose starts from the volume. If the real volume is 38 m³ and you work with "around 30", you are underdosing by 20% on every correction. The symptom is a pool that never stabilises and an owner convinced the products do not work.
Filtration. The filtration hours needed depend on the pump's flow rate and the volume. Without those two numbers, filtration time is a guess — and the water never really clears.
Leaks. On a pool with no pipework diagram, locating a leak goes from a two-hour job to exploratory excavation.
The Baseline: Five Numbers and One Sketch
This is done once, on a Saturday, and it serves for the next twenty years.
1. The real volume
Measure with a tape: length, width, minimum and maximum depth. For a rectangular pool with a sloping floor:
Volume (m³) = length × width × average depth
with average depth being the minimum plus the maximum divided by two. For irregular shapes, split it into sections. The full method is in How to Calculate Pool Water Volume.
Write the result on a sheet of paper and tape it to the plant room door.
2. The pump's flow rate
If the pump's rating plate is legible, the nominal flow rate is on it. If not, a professional measures it. With the volume and the flow rate you have the turnover time — and therefore how many hours you need to filter.
3. The clean-filter pressure
Do a full backwash and note the pressure immediately afterwards. It is the reference every future reading gets compared against. Without it, a pressure gauge tells you nothing.
4. The calcium hardness of your fill water
Measure the tap or well water you fill with, once. It is a stable number and it explains a great deal of the pool's behaviour through the year.
5. The lining type and its approximate age
It determines which products you can use and which will damage the surface. Liner, painted concrete, tile, fibreglass: each has different restrictions.
And the sketch
A pencil drawing, however rough, showing: the skimmer, the main drains, the returns, the plant room, and the approximate pipework route if you know it. It is worth gold on the day of the first leak.
💡 Dica Profissional
Do this exercise before you need it. The wrong moment to discover you do not know the pool's volume is the moment you have to apply an urgent recovery treatment whose dose depends on exactly that number.
What to Check on a Pool Built Without Plans
This is not a criticism: many pools built in stages work perfectly. But there are points worth checking, because they are the ones that cause problems years later.
| Point | What to check | Why |
|---|---|---|
| Electrical connection | Dedicated RCD, earthing, panel protection | The only item here that is a safety matter |
| Plant room location | Ventilation, drainage, distance to the pool | A closed, humid space corrodes equipment |
| Pump level relative to the pool | A pump above water level needs priming | It explains start-up difficulties |
| Number and position of returns | A single return creates dead zones | It explains algae always in the same corner |
| Pipework diameter | Narrow pipework limits flow | A bigger pump does not fix narrow pipework |
| Main drain | Does it exist? Does it work? | Without it, suction and circulation are limited |
| Multiport valve | Every position works with no internal leak | Internal leak = continuous water loss |
The dead zones point is the most underestimated. If the pool always has algae in the same corner, the likely cause is not the treatment: it is that the water does not circulate there. The fix can be as simple as aiming a return differently.
Vegetation: Pines and Generous Plots
Quinta do Conde and Fernão Ferro sit in the pine belt, with large plots and trees. That means pine needles, pollen in spring, and leaf fall in autumn.
The essential point: net them out before they sink. Needles release tannins as they decompose, which lowers the pH and darkens the water, and they release phosphates, which feed algae. Removed the same day, they do practically nothing.
We covered the mechanism in detail in Aroeira Pools: Caring for Them Among the Pines — it applies here in full.
The Basic Plan, No Complications
On a normal residential pool, with the baseline established:
| Frequency | Task |
|---|---|
| Daily, in fall season | Surface net |
| 2-3x/week | pH (7.2-7.6) and free chlorine (1-3 mg/L), at the same time of day |
| Weekly | Vacuum, brush, clean the waterline, skimmer basket |
| Weekly | Filter pressure against the reference |
| Monthly | Alkalinity (80-120 mg/L), calcium hardness |
| April | Opening and equipment check |
| October | Winterisation or reduced regime |
| Winter | Overhauls and replacements |
Common Mistakes
Dosing from an estimated volume. The origin of half of all chemical stability problems.
Not having the clean-filter pressure written down. With no reference, the gauge is decorative.
Buying a bigger pump to solve a lack of flow. If the pipework is narrow, a bigger pump does not help and consumes more.
Treating algae in one corner with more product. If they always return to the same spot, it is circulation.
Leaving the electrical installation unchecked. The only point on this list that is a safety matter.
Frequently Asked Questions
How do I find out my pool's volume with no documentation?
Measure with a tape: length, width, minimum and maximum depth. Volume = length × width × average depth, the average being the two depths added and divided by two. For irregular shapes, split into sections and add them.
How many hours should I filter?
Divide the volume by the pump's flow rate to get turnover time, and count two to three turnovers a day in the bathing season. Without those two numbers, any answer is a guess.
I always have algae in the same corner. Why?
Almost certainly insufficient circulation in that area — a dead zone. Check the orientation of the returns and brush that area more often. More product does not solve a hydraulic problem.
My pump struggles to start. Is that normal?
If the pump sits above water level it needs priming and some difficulty is expected. If it sits below and will not prime, air is getting into the suction side — the lid seal, a low water level, or a leak in the pipework.
Is it worth installing a main drain if I do not have one?
It significantly improves circulation and suction, but it is a construction job. Before that, check whether the orientation of the existing returns can be improved — it is far cheaper and solves part of the problem.
Is an older pool's electrical installation safe?
You cannot assume so. A dedicated RCD, tested, and proper earthing are the minimum. It is the only point on this list not worth deferring, and it is checked by an electrician.
Conclusion
On a pool with no history, the most valuable work you can do is not chemical: it is writing five numbers on a sheet of paper.
Key points to remember:
- Real volume, pump flow rate, clean-filter pressure, fill-water hardness, lining type. Five numbers, once.
- Sketch the pipework. It is worth gold on the day of the first leak.
- Algae always in the same corner is circulation, not treatment.
- Narrow pipework is not fixed with a bigger pump.
- The electrical installation is the only point that is a safety matter.
If you have a pool in Quinta do Conde or Fernão Ferro with no documentation at all, the on-site technical diagnosis establishes exactly this baseline — volume, flow rate, turnover time, equipment condition — and hands it over in writing. It costs €45, deductible from your first month under contract.
