After spending some time thinking about how to deal with the  top-heavy mature form of Lobelia cardinalis ‘Wavy’ even after a very aggresive trimming, I decided to pull it out and replace it with a (hopefully) smaller form:  Lobelia cardinalis ‘Dwarf’.  There are still challenges with aquatic plant supplies so when I got notified by Aqua Essentials these were back in stock I picked up two pots straight away.

These dwarf lobelias are grown in emersed form in rockwool by AquaFleur in the Netherlands.  When they arrived they were larger than I had expected and carefully prising away the rockwool with pinsettes revealed three good-sized individual plants per pot.  You’re never entirely sure how many individual plants will come in each rockwool pot –  the catalogs tend not to list this information – sometimes it’s one plant per pot, and other times a good many.

The pinsettes made planting easy.  There’s a perspective shift when looking through the aquarium acrylic walls at an angle and although I thought I was planting these towards the front, the side-on view showed they are actually about halfway back, which is fine.  The Lobelia cardinalis ‘Wavy’ adapted to submerged-form growth almost immediately, so I’m optimistic the dwarf form will as well.

The fish were very interested in checking out the new situation…

Nothing has really dramatically changed in the Fireplace Aquarium but I feel the green spot algae has been growing back quicker than it used to.  I was having to give the tank walls a credit-card scrapedown every three or four weeks, but now it seems up to every other week.  I tried increasing the dose of liquid carbon (a.k.a algaecide) from 1.0 ml per day to 1.5 ml per day, without noticeable effect other than using up 50% more EasyCarbo.  For sure though the hours of daylight are increasing rapidly now and even though the aquarium is 4m from the window, it is a south-facing window and bright all day long.  I’ve reduced the lighting supplied by the Tuna Sun LED light by reducing the period of full intensity light in the aquarium daily lighting sequence by 2 hours per day, so we’ll see if that helps.  I have long suspected that I’ve been providing more light than necessary so let’s give this a go.  I’m also going to knock the liquid carbon dosing back down to the original 1.0 ml per day.

Continue reading “Green spot algae in the summer”

Managing CO2 flow rate satisfactorily is particularly difficult for smaller aquariums; it’s very easy to have the CO2 come blasting out, but a nice steady well-controlled bubbling takes some work.  The usual combination of regulator and needle valve can work, and adding in a secondary flow restrictor between the two can be a big help.

Mott porous metal flow restrictors

Mott porous metal flow restrictor
Mott porous metal flow restrictor

Plastic flow restrictors that work “well enough” can be had for as little as £5, but I’ve always been enamoured of the porous metal flow restrictors from Mott corporation.  A metal disc has hundreds of microchannels fabricated into it such that the gas has to squeeze through to the other side.  By controlling the size and number of the channels and the shape of the disc, any desired flow rate can be achieved for a defined gas supplied at a defined pressure.  I managed to score the pictured one from Ebay.

Fireplace Aquarium Mott flow restrictor

Mott calibrates the flow rate against nitrogen gas with an input pressure of 30 PSI which is a typical regulated gas output working pressure.  The one I got is calibrated to 10 SCCM (standard cubic centimetres per minute) which is to say, 10 ml.  CO2 is less viscous than nitrogen, so this restrictor outputs a flow of 12 ml / minute CO2.  I find that for the 8 hours per day the CO2 is flowing through the aquarium (controlled by a solenoid on a timer) I need a flow rate of 6 ml / minute CO2, or maybe slightly less, so this is the perfect flow restrictor for this set-up.  Given an input flow rate of 12 ml / minute CO2 the needle valve has no trouble at all comfortably getting the flow rate down by the remaining 50% needed.  With the new restrictor in place adjusting the needle value smoothly moves the flow rate up and down, with none of the twitchiness exhibited with much higher input flow rates.

Continue reading “Managing CO2 pressure”