Red Algae- K rend

Hi guys,

just after a little of advice on a enquire regarding a render clean. I’ve cleaned several walls now but all been normal green algae. This is red algae.

I remember reading that red algae can be difficult to get rid of? I’ll attach a picture below.

Would You biocide? Or would a 1.75-2% mix or hypo normally be ok?

For instant clean hypo it 3-4 % and re apply until it’s gone giving a light rub with wfp , bio will take weeks to remove that and look anything like acceptable for the customer from my experience 

Pjj said:

For instant clean hypo it 3-4 % and re apply until it’s gone giving a light rub with wfp , bio will take weeks to remove that and look anything like acceptable for the customer from my experience 

Click to expand...

Hi Paul,

Yeh, I explained that to him. I’ve not used a biocide yet so wasn’t sure how long exactly it would take, but also wasn’t sure hypo would definitely remove it. So 3.5%ish hypo not too strong for k-rend?

Start with a weak mix, maybe 2.5% mix applied from the bottom of the house up through a WFP, leave for 30-45 mins and rinse off with fresh water from customers tap if possible, re-apply if necessary and repeat.

Use a decent surfactant to make it stick.

Dennis Taylor said:

Start with a weak mix, maybe 2.5% mix applied from the bottom of the house up through a WFP, leave for 30-45 mins and rinse off with fresh water from customers tap if possible, re-apply if necessary and repeat.

Use a decent surfactant to make it stick.

Click to expand...

Thanks. Obviously parts of the wall are ok, some parts are really stained. If the red algae comes off with 3.5% strength (for example) I presume I do the whole wall with that? But I was always under the impression anything more than 2% was too much for k-rend?

RWCleaning said:

Hi Paul,

Yeh, I explained that to him. I’ve not used a biocide yet so wasn’t sure how long exactly it would take, but also wasn’t sure hypo would definitely remove it. So 3.5%ish hypo not too strong for k-rend?

Click to expand...

obviously use the weakest mix needed , but we have used 3-4% with no ill effects and it will kill it off quicker , use a neutralising agent or rinse with copious amounts of water and that will look like new , I have posted several times one job we did at that strength in -2 degrees with 3 month out of date opens drum of hypo , make sure that the walls are saturated with water before you start and you will use far less product .   

Pjj said:

obviously use the weakest mix needed , but we have used 3-4% with no ill effects and it will kill it off quicker , use a neutralising agent or rinse with copious amounts of water and that will look like new , I have posted several times one job we did at that strength in -2 degrees with 3 month out of date opens drum of hypo , make sure that the walls are saturated with water before you start and you will use far less product .   

View attachment 16404

View attachment 16405

Click to expand...

Thanks mate. That’s such an awesome before & after almost looks photoshopped haha....

Dennis Taylor said:

Start with a weak mix, maybe 2.5% mix applied from the bottom of the house up through a WFP, leave for 30-45 mins and rinse off with fresh water from customers tap if possible, re-apply if necessary and repeat.

Use a decent surfactant to make it stick.

Click to expand...

With respect you shouldn’t start at the bottom that’s an old wife’s tale about not leaving streaks , start at the top and let it run down with gravity you don’t need to spray the bottom 1-2 feet as it will natural run down to the bottom this will also prevent so much product going on the grass or path ways , trust me it will work much better give it a try . You don’t need to rinse between applications you can just keep applying the product and give it a light rub with wfp , then one really good rinse will do the job , works out quicker and less water run off to deal with . 

RWCleaning said:

Thanks mate. That’s such an awesome before & after almost looks photoshopped haha....

Click to expand...

Lol I can assure you there is no doctoring of these pictures , as this is a mid terraced house it just shows up the before and after so well we have a large portfolio of pictures like this that I use to show potential customers ranging from this small job to big blocks of flats and hotels that we have done but I think these pictures are the most dramatic 

I think you're complicating it too much @RWCleaning #H10RJD

clean with 3 to 1 mix u may need 3 applcations then bio as k rend will still have algi hidden the bio will suck out the remaining or you can just bio it that usly takes 3 to 5 days to shift red algi the only thing with bio is it wont tuch black algi