When using Rowaphos in a small aquarium there can be a slight dip in Ph after use for around 24 hours, Alkalinity drops are not often observerd but there can be a drop if …

• Too much Rowaphos is used, We suggest 100g per 400L.
• The aquarium runs low Magnesium levels. Correct levels of Magnesium can reduce or prevent calcium carbonate precipitation in that it prevents calcium carbonate seed crystals from being formed. Once seed crystals start to be produced it can cause a cascade precipitation event and Alkalinity will start to drop.
• If high PO4 is reduced quickly at the media surface and Magnesium is low this can cause temporary precipitation of Alkalinity/Calcium until the surface of the media has been coated, this then interferes with PO4 uptake.

If you see precipitation when you add the KH buffer you may be causing the total Alk of the aquarium to drop rather than increasing it, again due to cascade precipitation .This will also precipitate on all surfaces including the Rowaphos reducing its effectiveness.

Be mindful that in a small body of water any Alkalinity or Calcium additive may cause precipitation as it doesn’t have as much time to disperse as it would in a large body of water and concentrations can be very high locally if added too quickly. In such situations we would suggest splitting up the dose of the buffer in to smaller doses that are added slowly throughout the day.

Also check that your Calcium and Alkalinity levels are in balance.

In some cases, on small aquariums it can be best to carry out a few small water changes to balance out the KH and calcium levels if required.