Aptus - RO Water Conditioner

A mineral water treatment for reverse osmosis and soft water, with calcium and magnesium. You dose it on your source water rather than on your plant: 1 in 2000 for RO water, 1 in 4000 for soft water and 1 in 10,000 for tap water. From the first watering to the last, and always first into the tank.

The dose depends on your tap, not on your plant

For nearly every bottle on this shelf, the plant decides how much you give: the stage, the week, the size of the crop. This one is different. Aptus give three doses, and they vary not by growth stage but by type of water.

• RO water: 5 ml per 10 litres, or 1 in 2000
• Soft water: 2.5 ml per 10 litres, or 1 in 4000
• Tap water: 1 ml per 10 litres, or 1 in 10,000

The fivefold gap between RO water and tap water says a lot about what this product is for. A reverse osmosis unit strips almost everything out of the water, including the calcium and magnesium that tap water brings with it. The less your water has to begin with, the more you put back. On tap water the dose is small because most of the hardness is already there.

In practice you set the dose once, when you know what comes out of your tap or your unit, and keep it for the whole grow. You do not raise it in bloom and you do not taper it towards harvest. If your water changes, say because you move from tap water to RO, your dose changes with it. If only your plant changes, it does not.

What is wrong with water that has no hardness

RO water has a reputation for being clean and predictable, and for what is in it that is true. The drawback is what is not in it. Water without dissolved minerals has nothing to absorb a change, so a pH you set carefully does not stay put on its own. Growers on RO know the pattern: a tank that was right in the evening and somewhere else the next day.

Aptus describe the action like this: the calcium and magnesium in this bottle give the water its hardness back, and that makes the pH more stable. That is also the only job they give it. No growth, no bloom, no yield. Just water that behaves predictably before everything else goes in.

First into the tank, even before Regulator

Mixing order is not a detail with this bottle. In the Aptus schedule, Regulator normally goes into the clean water first, ahead of the boosters and the base feed. On RO or soft water this bottle moves in front of it: Aptus explicitly put it first of all.

The logic follows from the role. First you turn bare RO water into usable water, and only then do you start feeding. The order becomes: water, RO Water Conditioner, Regulator, then the rest of your schedule, and finally your pH check.

It does not replace CaMg-Boost

Calcium and magnesium on the label, and yet this is not a Cal-Mag in the usual sense. Aptus say so themselves: RO Water Conditioner does not replace CaMg-Boost, and if you use CaMg-Boost you keep using it to feed the plant.

The two do different things on a different clock. This bottle corrects the water, throughout the grow, at a dose set by your source. CaMg-Boost feeds the plant from the third week of bloom, at a dose set by the stage. For anyone growing on RO it also fills a gap in the Aptus schedule: CaMg-Boost only starts in bloom, so during vegetative growth there was nothing in an RO tank to give the water any hardness.

What is in it

Aptus list calcium, magnesium, nitrogen and a small quantity of trace elements. They publish no guaranteed analysis with percentages, so we do not quote one either. They also state that it contains no chlorides and no heavy metals and dissolves fully in water.

The nitrogen is worth noting if you feed precisely. It is a small amount at this dilution, but it is a nutrient, and everything this bottle adds to the water counts towards the EC of your tank. So measure your EC after adding it, not before.

Available sizes

Technical Specifications:

• Type: mineral water treatment for RO and soft water
• Manufacturer: Aptus
• Contains: calcium, magnesium, nitrogen and a small quantity of trace elements
• RO water: 5 ml per 10 litres (1 in 2000)
• Soft water: 2.5 ml per 10 litres (1 in 4000)
• Tap water: 1 ml per 10 litres (1 in 10,000)
• Period: the whole grow, start to finish
• Mixing order: first into the water, before Regulator
• Substrate: all substrates
• Free from: chlorides and heavy metals

Frequently asked questions

Do I need this on ordinary tap water?
Usually not, because tap water already has hardness of its own. Aptus do give a dose for it, 1 in 10,000, but the product is made for RO and soft water.

Is this the same as a Cal-Mag?
No. It corrects your water throughout the grow. A Cal-Mag such as CaMg-Boost feeds the plant during a particular stage. Aptus state clearly that one does not replace the other.

Should I raise the dose in bloom?
No. The dose depends on your water, not on the stage. You only change it if your source water changes.

When do I add it?
First of all into the clean water, even before Regulator. Then the rest of your schedule, and the pH check last.

How far does a bottle go?
One litre treats 2000 litres of RO water, 4000 litres of soft water or 10,000 litres of tap water. The 5 litre goes five times as far.